Here's a few that jumped out at me:

ECU - Eternal Care Unit: heaven ("gone to the ECU = dead)
FLK - Funny Looking Kid (sometimes suggests rural inbreeding)
Lignocephalic - wooden-headed (i.e. dense [thick] or stubborn)
Solomf yoyo - So long, mother-f*****, you're on your own
WNL - Will Not Listen; patient won't take medical advice

Read them all.