If a man is married with a family, and has a child with another woman while still married. The bastard child is the the "side kid".
Autumn Jackson would be Bill Cosby's "side kid".
di Matt, Jeff, Chad 22 settembre 2007
Referring to children you've had outside your marriage with other women.
Got any side kids? Nah just the one with my wife
di Toolz 12 settembre 2007