Usually a farewell statement at the end of a conversation. Rather than saying "Goodbye!" You can Say, "Don't forget to lick my boner!" Or to further confuse the other person, it can be abbreviated to "DF2LMB"
Mom: Son, could you pick me up a loaf of bread on yer way home?
Son: Sure, mom, no problem.
Mom: Ok, son, thanks! See you soon.
Son: Yer welcome, mom. DF2LMB!
Mom: What the fu---