A bellshabob doesn't have a solid definition. Originally designed as a shish-ka-bob of bells. Normally used in the phrase "You bet your bellshabobs" as an affirmative. If asked for the definition, you must give an outrageous answer that's never been used before.
"Hey Sarah, you wanna go to the mall?"
"You bet your bellshabobs."
"Hey Joe, what's a bellshabob?"
"A rare type of STD that looks like gold chickenpox on your dick."