Poker term used to describe when two or more "coolers" are dealt in the same hand. An example of a freezer would be if one player was dealt AA, another KK, and a third QQ.
More commonly seen with online poker rooms such FullTilt, Pokerstars, or Cake.
At the WSOP last year, some amateur donk won it all on a fucking freezer. Stacked a player with AA and another guy with KK when he flopped a set of Queens. Unbelievable.