Jelloface is a name for someone who is somewhat fat, this is a nicer name for them considering you probably don't want to call them fat to their face. Jelloface is implying their face is squishy, therfore fat. Or it can be used to call someone fat behind their back without it being ovbious.

It can also be a pet name for a close couple, not implying fatness in this case. Something like cutie.

Adj. Something that is expected to have a long lifespan by virtue of having existed for a long time, based on the lindy effect, named for the New York restaurant Lindy's, coined by Albert Goldman and popularized by Nassim Taleb.