This is an exclamation of laughter and joy similar to LOL or LMAO. It stands for...
Rolling
In
My
Pants
Laughing
It can be used in any situation when one wants to express laughter in a fun, jubilant way!
Evan: I just ate 15 clementines and now i feel really sick...
Ben: hahaha I just rimpled!
22👍 7👎