After white people takenormal group pictures, one adult usually uses 'silly one' meaning taking an abnormal picture. Thus can involve Fingerguns, duckfaces and wide open mouths.
Marcelo: Let´s take a group picture!
Someone: *takes picture*
Elisabeth: And now a silly one!
to give someone an exceptional blowjob; the sloppiest toppy imaginable.
My girlfriend really sucked me silly last night.
If I lose this game of Uno, I'll suck you silly.
That woman from the Grapefruit technique videos really knows how to suck one silly.