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1.
I game or a prank younger people play which involves knocking on someones door and leaving before they answer
you wanna go bobby knocking later?

yeah sure
by Ian Handley September 14, 2006
 
2.
The act of repeatedly slapping one's member against the face of one's partner during foreplay.
I was Bobby Knocking my girlfriend last night, which turned her on immensely
by Barry_2007 August 25, 2007
 
3.
The act of repeatedly slapping one's member against the forehead or face of one's partner during foreplay.
I was Bobby knocking my girlfriend last night which turned her on immensely.
by Barrington_2007 August 20, 2007