RP

RP stands for "roleplay" (which may also be spelled "role play" or "role-play"). This acronym is most often used by those playing RPGs, but may be used by anyone who is engaging in a bit of make-believe.

When roleplaying, a person affects the personality and behavior of a (usually) made-up character. For example, players of DnD often roleplay as fighters, wizards, rogues, and other fantasy characters.

However, anyone can engage in roleplay, and roleplay does not need to involve fantasy characters or even RPGs. For example, therapists often engage their clients in therapeutic roleplay, and some couples (and throuples) enjoy roleplaying to spice up their love lives.

A baseball position played by the pitcher who replaces, or relieves, other pitchers.

The relief pitcher comes into a game to replace the starting pitcher or another relief pitcher. He can sometimes pitch just one pitch or multiple innings depending on the situation. The relief pitcher that comes in to end the game is often called a "closer" and usually pitches the ninth inning to preserve a victory. Baseball acronyms, such as SP and RP, are commonly used on team rosters and Fantasy Baseball to signify a player's position.