Term from the British comedy series The Mighty Boosh, Season 2. Used in the episode "The Legend of Old Greg." Basically a kid-friendly version of motherfucker.
Howard: That's not my fishing line
Greg: It's attached to your rod, motherlicker.
This is what LADS say when they can't swear and say "Dumb Motherfucking Bitch" as both the school and the parents don't allow children to swear...
"Stop stealing my toys you Diddle tootie footie ritty booty motherlicker!!!"
Or
"That Diddle tootie footie ritty booty motherlicker is the worst guy I have ever seen..."