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when one visits the bathroom to relieve ones self of bodily waste, they are giving birth to bum babies. Bum babies come in all kinds of varieties, brown, greeney-brown, fat, thin, nutty, the list goes on...
Vicki, I just gave birth to a bum babies, it was so beautiful that a tear of joy rolled down my face.
by Dave matthams January 24, 2007
Noun: A derogatory term used to describe someone who is so retarded that they were likely conceived as an atrociously tragic accident through penetrative bumsex.
Bill: Did you see Ali on Friday night acting like a complete donkey?
Ted: Yes! She's such a fucking bumbaby.
Bill: Dude. Sweet call.
by psuedonymtastic adventures July 26, 2011
A poo
"Man, I just did a massive bum baby"
by hgutj January 07, 2012