The melee grab feature is initiated when an enemy is close enough and an on-screen prompt to press the 'use' key (E by default). This move will always kill the intended target and sometimes leaves Sam holding a 'trophy' which is usually some part of the enemy's body. The trophy can be dropped or thrown, although using it as a thrown projectile is fairly weak. The melee grab only works on certain types of enemies. Other enemies are either invulnerable to the move or too large (no prompt will appear to execute a melee grab).
When it is Christmas, Sam can "decorate" the Christmas tree that appears on every level with each type of trophy, including a Gnaar's eye, a Kleer's skull, and a Rocketeer's heart. When the tree has been decorated, it will light up and the Christmas theme from The Second Encounter will play.
Kleer Skeleton; Sam will sidestep and grab the Kleer in a headlock and promptly pull the Kleer's head off, leaving Sam with a held trophy.
Hatchling Arachnoid; Sam will break the Hatchling's neck, which instantly kills it. This move cannot be performed on the adult Arachnoid.
Scrapjack; this move can only be performed if the Scrapjack is stunned (he appears to be hunched over, but still standing). Sam will rip off Scrapjack's faceplate and kiss it, leaving Sam with a held trophy.