When a person gets overly excited and starts laughing, while rolling on the floor.
Jimmy; Hey! Why did the chicken cross the road?
Ryan; I don't need to know....because it's ROFLTIME!
.
Jimmy later switched to geico, saving a bundle on car insurance.
Rolling On The Floor Laughing With Tears In My Eyes
Much like its root word rofl, but it offers much more insight into the level of hilarity of the situation. Although yes, you are indeed rofl'ing, you are also doing so with tears in your eyes, which tells the rofl-ee that you found them, their joke, or the current situation worthy of more than just a rofl.
Jake: "He was all like...lawl?"
Mortimer: "...gg"
Jake: "ROFLWTIME!!"
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.