Brilliant. I don't think that two words by themselves have made me laugh so much in ages. It is truly witty, and has gone a long way to restoring my faith in intelligent life on dA. (After a depressing day wincing at the language-abuse in the forums).
You have no idea how much i use the this notation [sic] . . . it is my everyday companion . . . my clients usually ask me what it means . . . oh, just a stamp of a flagrant error, Pontius Pilate washing his hands, lol
Don't feel too much like a moron - 'sic' is a fairly obscure editing reference in literature, or writing in general. You might see it from time to time, usually in a text book or magazine where they are quoting someone else. As the definition explains (see [link] ) it's often a way of saying in print 'yes, I know that this is gramatically wrong, but that's the way it was written originally - don't blame me.'
In the case of the cup, it is gramatically incorrect to say 'thats' if you mean 'that is.' There's a missing apostrophe before the 's'. It should be that's.
So the cup is saying That is Sick, but it's also saying - 'i KNOW there should be an apostrophe in there.'
It's a very clever two-pronged play on words.
(unless of course bananaprincess had something else in mind, in which case I've just made a fairly complete idiot of myself!) I hope you don't mind me jumping in and replying - i was very bored)
BTW, a person who worries about feeling like a moron but asks for an explanation usually isn't. A moron would be happy in his/her/its ignorance.