LOL, I thought it was I Laughed Til My Guts Were Falling Out" and you'd put a U instead of an O, but then figured the "FU" may have been for, errrm, something else :D
That would explain the necessity for an ambulance...
ILTMGWFU :D
Whats the U stand for? :D
Oh, don't tell me I've got the acronym wrong? I thought it was "I laughed till my green wellies filled up"?