PC.net

SEAL

Meaning Slaying everyone and laughing
Type Acronym
Rank ★ ☆ ☆  Uncommon
Usage Online Only (chat, messaging, e-mail)
Comments

Used in online multiplayer 3D shooter games, such as Quake and Unreal; typically stated when a player gets multiple kills in a row.

Updated March 3, 2014
Information from PC.net
https://pc.net/slang/meaning/seal
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