A bellybutton bargain is someone who is rather large/heavy/fat/overweight/or pleasantly plump.
It can also mean that someone has an obsession for bellybuttons
Bargwash, the expression to use when things don't go your way, or end up going to complete shit. People find the spoken word of "bargwash" is enough to describe its meaning.
That night on the beach was total bargwash after we heard a kid got bit in the face by a shark.
When John found out Sally was a man, his plans went bargwash.