Acronym for "fucking wish could laugh out loud". Used when you have received a hilariously funny text, e-mail or instant-message where "lol" would normally apply, but you have to contain your laughter because there are people around, e.g. at work, in church or when the person at the butt of the joke is nearby.
2 people I.M-ing at work:
-"hahaha you were so wasted
last night, how did you end up in that bunny costume with a condom on your nose?"
-"omg, had forgotten...all coming back to me now....."
-"fwclol just thinking about it!!"