A giant, slow-growing, epic-ly painful zit
. The kind that you can't pop successfully for days even though it resembles a small volcano on your face, because its source is so deep. Often used as part of the phrase "massive underburner."
This term was coined by Alice Thomas in Columbus Ohio, in approximately 1993.
I have a giant underburner on my chin.
I wish I could pop this dang underburner!
Look at this massive underburner!