The next generation of the usage of lol. Lol is outdated and now cliche. If you really want to express that you are laughing, lol++ is lol incremented; meaning an added kick. Can also be used in chat etc. to indicate a laugh after a laugh.
Person 1: Dude, I crashed my bike into a tree last night. Person 2: Lol. Person 1: Yeah, I was so drunk, i ended up laying in the ditch until this afternoon because I couldn't crawl out of it in my stupor. Person 2: Lol++.