18th century slang for a child born out of wedlock.
As well as having a daughter with his wife, Ben Franklin fathered a by-blow by another woman. (This is true).
Gas that escapes between the wall of the anus and the poop that needs to come out.
Hey Ralph, you smell that! I have to shit so bad I've got blow-by.
A condition exhibited by a worn-out internal combustion engine when the piston rings no longer efficiently seal the combustion chamber, allowing compressed air and fuel to escape the cylinder and thus power is lost and emissions are increased. The engine also usually burns oil.
I was going to buy that 350 from Carl, but it had too much blow-by and needed to be rebuilt