masturbating with a marshmallow in your ass and farting and burping at the same time, hence the word "bart" = burp + fart. The fart can often be used to warm the mallow in prep for a smore.
Wow I'm having a lot of gas, I'm horney, and I would love a smore...I feel like marshturbarting
A person you hate intensely not because they deserve such hatred but because they serve as a focus for your general hatred. A healthy way to dispense with excess animosity.
Jake's not really that big an asshole. He just serves as my hate sink.