taking a fatty crap; the porcelain bus is another word for toilet, while riding it involves sitting on it &, well, pooping.
he's busy riding the porcelain bus... he won't be back for a while.
by becca vajayjay October 13, 2006
puking into the toilet.
Damn I drank a whole case last night and now I'm riding the porcelain bus.
by Nick D February 13, 2003