slip one past the goalie/keeper/goaltender/etc.

1. To score a point by getting a ball, puck, or similar object past a player assigned to protect their team's goal. The striker slipped one past the goaltender with a brilliant shot to the corner of the net. Despite the team's fantastic defensive display, the Red Wings' forward managed to slip one past the goalie with just two seconds left on the clock.

2. euphemism To impregnate a woman, especially when unplanned or undesired. Hey, I try not to judge anyone's lifestyle choices. Just make sure you don't slip one past the goalie unless you're prepared to face the consequences. A: "Tom and Kate are having another baby." B: "I thought they said they were done after three? Maybe Tom slipped one past the keeper."