Ok, let’s hear some of the naughty mnemonics (or otherwise exaggerated, ridiculous and memorable stories) people have made up to remember these frustrating characters!
吞
– person spread eagle with another’s mouth right between the legs. Fits the meaning as well. 
火: I can’t type Chinese, so I had to cut and paste that. Hope it shows up right. Fire: I picture a Person flailing his arms because he’s on fire. Not that complicated, but it’s kinda sadistic, so it’s my fav!
The character for one is one hard-on, and the character for two is two hard-ons. The character for three is three hard-ons. The character for person is one big hard-on resting on a smaller hard-on. The character for middle is a hard-on too long to fit. There are no characters that do not contain hard-ons, and this is why there are so many Chinese people.
吊 = hang. It’s a guy who’s uh…well hung.
bob has the right idea, as usual.
i don’t have any Chinese character mnemonics, but there was one i used to have a bit of a titter at in medical school.
there are twelve cranial nevrves, each of which is known by a number (roman numerals) in the order of its appearance from the ‘central nerve cord’ or by its longer name. they are a bugger to get in the right order, so there is a handy mnemonic which many people have as
o o o to touch and feel a girl’s vagina and hymen
which i may still be able to remember as
olfactory optic oculomotor trochlear trigeminal abducens facial auditory (now called the vestibulocochlear) glossopharyngeal vagus accessory hypoglossal
there are many other mnemonics for this set, not all of them rude.
http://en.wikibooks.org/wiki/Transwiki:List_of_mnemonics_for_the_cranial_nerves
another list to remember was whether they were sensory, motor or both (mixed) nerves…
Some Say Money Matters, But My Brother Says Big Brains Matter More
God damn! I may have passed neuro if I’d learnt that one instead of: On Old Olympus’ Towering Top A Finn And German Vault and Hop.
Erh, hang on, I still remember that one, but can’t decode it anymore.
HG
As some of you likely know, very close to that graph’s structure, its pronunciation and its meaning is 屌. I’ve read that the slang term diao3 for ‘male naughty bit’ is written 屌, and that an alternate way to write it, 鳥 (normally read ‘niao3’, bird) was also pronounced diao3 in this context and was used in early novels.
Along those lines, the near-homophone 了 liao3 has been hypothesized by 馬敘倫 Ma3 Xùlún to be (etymologically) a depiction of male genitalia (there are other theories too). Its vertically inverted form (now obsolete) was also pronounced diao3 and meant ‘hang, dangle; phallus’.
Continuing in this vein, 亨 heng1 ‘fortunate’, 哼 heng1 ‘moan’ and 享 xiang3 ‘enjoy’ are, er, hard to keep straight, at least the first and last are – but the first two could certainly use Ma’s interpretation of 了 in a mnemonic.
For the first, 亨 heng1 ‘fortunate’ also looks like a guy (with a beret) who’s ‘well hēng’ and therefore ‘fortunate’. 哼 heng1 ‘moan’ is an easy extension of that – you can imagine what the mouth bu4shou3 is there for.
The third, 享 xiang3 ‘enjoy’, is 子 Confucius (as in 子曰) “enjoying” a 口-job under 
the covers.
Now see, DB? If I’d had you earlier in my Chinese-learning career, I might be able to write today. (But probably only about certain subjects! 
)
For 己 ji3 ‘self’, 已 yi3 ‘already’ and si4 巳 ‘*fetus?; 6th Earthly Branch’, the upper left of which are open, half open, and closed respectively, I used something like ‘one’s self must be open’ (I myself will strive to be open-minded) for the first, and ‘already half closed’ (like my cat’s eyes, when falling asleep) for the second. Just memorizing those two verbal phrases was enough.
For 侯 hou2 ‘marquis’ (which appears to have a 人部 ‘man’ bushou, actually a corruption – explained further below) and 候 hou4 'wait; season; time’, which in my experience are really hard to remember (which one has that extra vertical stroke in the middle, dammit?), memorizing this mnemonic phrase was what finally solved the problem:
'The marquis is a corrupt man, but wait –in time he’ll bear a son’ . The ‘son’ refers to the smaller, extra stroke standing next to the real ‘man’ element in 候. The ‘wait – in time he’ll bear a son’ helps you remember which of the two graphs has this extra stroke, and the whole phrase also helps remind you which character (候, not 後) to write for ‘wait’ and ‘time’. It even tells you which character is corrupt.
To explain that corruption, although this is not part of the mnemonic, note the top of 危 and top right of 陷. those two strokes are a person (just atop, rather than beside the character). That’s what the top of both 侯 and 候 was. They (if you remove the person-side from the latter) are supposed to be the same graph and actually contain exactly the same strokes, just slightly disjointed in each. They both comprise that person-top, plus 厂 an archery target (the two strokes slightly disjointed in both modern versions) plus 矢 shi3, an arrow. In 侯 the first stroke of the person-top has become disjointed, and incorrectly attached to the left side of the archery target, which has also become disjointed. Together, they have been misinterpreted as a person-side bushou. So in actuality, only 候 has a person-side bushou. The other man is a corruption (as my above mnemonic reminds you).
DB, how are these naughty?
[quote]Ok, let’s hear some of the naughty mnemonics (or otherwise exaggerated, ridiculous and memorable stories) people have made up to remember these frustrating characters![/quote] 
窮
– lacking, poor
This character is really easy to remember. A poor person has no house to live in so he must live in a small cave (aka, hole on the side of a hill). To get in, he must bend 弓 his body 身 to get inside the hole 穴. This has been such a useful mnemonic that I have a harder time remembering the simplified version of the character, 穹.
This is why context and character juxtaposition is a better way to learn to read Chinese to a reasonable level for most people. Even if I am unsure which exact character it is I can quickly guess from the context. Sure you won’t be reading too many novels or writing them but you’ll be functioning without going through years of memorisation to get there. But hats off to people who are willing or have interest to put in the effort.
I love 爽 ‘shuang3’ meaning ‘cool’, it looks to me like a person that is jumping around or spraying out light or something.
I had a friend that thought 鼎 looked like a girl getting eaten out (upside down, sorta like that Red Dog beer)
[quote=“urodacus”]o o o to touch and feel a girl’s vagina and hymen
which i may still be able to remember as
olfactory optic oculomotor trochlear trigeminal abducens facial auditory (now called the vestibulocochlear) glossopharyngeal vagus accessory hypoglossal[/quote]
My dad tells me when he went to med school in the Philippines, he used: On Ol’ Obando’s tower top a Filipino army guards villages and huts
And when my brother was in med school, he used: Oh Oh Oh to touch and fondle a girl’s vagina spells heaven (where S = Spinal accessory nerve)
To remember the order of the main Chinese dynasties: Qin, Han, Sui, Tang, Song, Yuan, Ming
Quietly he stroked the soft young manhood.
Quit hanging suits tangled, some mongooses mind. (where the first M = Mongol)