black bottom lighter
Refers to the bottom part of a lighter (usually a BIC) that has been colored black due to the amount of times it has been utilized to compact ash and residue from smoking pot in a bowl.
You can tell that this black bottom lighter has put to good use!
Bottom lighter
A person who smokes a substance(crack,meth,dabs, etc.) that is lit from the bottom.
Look at the methed out loser he is a real bottom lighter