ash cash - payment received for filling out a cremation form
bash cash - payment for verifying assault claim
houseplant - junior house officer (first year doctor)
killing season, the - period around August in which freshly minted doctors (houseplants) take employment.
LONH - patient with a suboptimal Glasgow Coma Scale score.
P3 - standard A&E treatment (paracetamol/penicillin/discharge)
PGT - inebriated, involved in an altercation
PFO - inebriated, everything spinning
PDA - inebriated, denies all
supra-tentorial - problem is located above the tentorium cerebelli
top and tail - endoscope in both ends of the gastro-intestinal tract
TTFO - asked to leave, usually the emergency department
I'll add a few more as they come to me.