- or -
You cheatin' MFer, wait til you see your car!!! MLOL MLOL MLOL!!!!
1. When you're not sure if "lol" is the right thing to add.
2. If you don't know if your laugh will be received appropriately, and the other person will take offense to you laughing.
3. If you are not sure the other person finds something as funny as you do.
Dave: "Yeah, lol! :)" or "Yeah, rofl!"