A grand slam occurs when a batter hits a home run with men on first base, second base and third base. Four runs score on a grand slam -- the most possible on one play -- and a batter is awarded four RBIs.
Understandably, a grand slam usually has an immense impact on the result of the game, because four runs score on the play.
Grand slams are rare. They are also entirely a result of the circumstances, meaning some of the game's greatest sluggers haven't hit many grand slams simply because the situation (three men on base) doesn't present itself often.
The term originated in the card game Bridge, referring to a player winning every trick. It carried over into baseball because it refers to a team scoring as many runs as possible in one at-bat.
In A Call
"slam," "salami," "grand salami," "grand-slam home run"