an acronym for Pointless Build Up.
Used when a seemingly interesting story comes to a sudden and often disappointing finale. Or used to stop a story in the middle by the story teller upon realisation that the tale isnt going anywhere. Aimed at saving or explaining poorly told stories
"i took the bus into town the this morning and sat beside this total babe, she had the sexiest whitest smile, big boobs, and and rip in in the inner thigh of her pants, and she was staring at me the whole time. i knew she wanted it. then she got off at the next stop."
"dude, what a pbu"