The sexual act of surprising your partner by making your finger limp and wiggly, like that of the jelly inside of a donut, and forcefully inserting it into his or her rectum.
I suprised that skank when i gave her the ole jelly finger.
A sticky purple or red substance found on a child's hand as a result of being a little kid. Often found on the back of DVD's, CD's, or any other valuables.
Get your jelly fingers off of my stuff!
To wobble one's finger savagely in close proximity to another's 'butthamper'
'I jellyfingered your butthamper'
'...no you didn't'