When you go out of an evening, or hang out with your bestest and have so much fun that there is a risk of reaching the limit and beyond....
(there's a hand gesture too -
make the letter "T"
then, wave your hands in the air like you are having TMF!!!!!!)
Fancy a bit of TMF later...We are off dancing!
"Man, How much fun was last night?""
"I know!!! Too Much Fun!!! TMF baby!"