Alone, tranny is used as a greeting among gay men.
Gay#2: HAAAY tranny!
Gay#1: Tranny, you are a hot tranny mess today; what'd you do last night?
The term is now used to describe generically anyone (regardless of sexual identity) who is any of these: a fashion nightmare, a bad dancer, sloppy drunk, has atrocious manners, tells hilarious off-color jokes, is very funny, is flamboyant, or whose life is in shambles or an endless comedy of errors.
Oh, my God! That's too funny! You crack my ass up, you hot tranny mess!