I have a few spoons with these little nipples poking out from the side of the bowl. i've always wondered what it's there for? Heres a pic of what im talking about. cant post a pic actually so heres a link jesus christ i cant do it nothing is working... there we go
I think just decoration. I also like the way they add 'grip' to a pipe. Sometimes you will see pipes that use the glass blob as a magnifying glass for a small design underneath it, always thought that was cool.
Its a choke, so there's no air lowing through so al the smoke builds up. When you release the choke then you get the big hit of all the built up smoke. You'll notice a totl difference in the size of your hit if you do this. Atleast for bongs, and that how I learned about bowls.
Im pretty sure OP was talking about the little glass warts/bumps that some spoons have, not the carb hole. Yeah theyre pretty much just to add some flare to the piece and give you a better grip.
Ah, I can't see them and that how a newbie friend described the choke to me as a nipple on the side of the bowl.