To look in your pockets for an item, to find its not there, and then begin to frantically search everywhere to finally find said item was in your pocket all along.
I just spent five minutes looking in my room for my key and it was in my pocket the whole time! I bilboed out, big time!
When you stick your big toe (bilbo) in a guys ass and honk a tit of another person at the same time while masturbating with the free hand
Thanks for coming over last night frank, that honking bilbo was the best orgasm ive ever had.