I remember reading an edition of Tips & Tricks magazine’s cheat code books, and upon stumbling into one of the PS2 pages (keep in mind that this was before cheats for the Xbox and GameCube were present), I remembered seeing an article on one of the Unreal Tournament games for the PS2 and how an unlockable modifier would make a character gain weight with each frag. But, I can’t seem to remember which PS2 edition of Unreal Tournament it was… 
UPDATE: Now I remember! It was the original 1999 game, and the modifier was named Fatboy! 