The act of your Blowing a load into your girlfriend or wife's mouth during oral sex. Then the girlfriend or wife transfers the load to the asshole that was hitting on her all night at the party, The very asshole that also managed to pass out at yours or her house. Completion of the Aberdeen Snowball is when said victim and Asshole is told in the morning what happened.
"Mike was hitting on Lacey last night, so after he passed out she helped me give him an Aberdeen Snowball. "
"There's nothing better than informing someone that they received an Aberdeen Snowball last night!"