Mister Sandman (Fallout: New Vegas)

Mister Sandman is a perk

Effects
With this perk, the player character has the option to silently kill any sleeping Human or ghoul. Mister Sandman kills give a base 50 XP per kill, which may be increased by the Well Rested status effect and the Skilled trait.

Mister Sandman is performed in sneak mode and by choosing "pickpocket" on an unfortunate sleeping victim. The game pauses and brings up a menu with the options to "murder" or "pickpocket". Choose the former to activate the perk. When used, a short murder animation follows with the character cautiously looking around and slitting the victim's throat, accompanied by a cartoony jingle.

Behind the scenes
The name of the perk is in reference to The Chordettes 1954 song "Mr. Sandman." While the perk has existed since Fallout 3, the song itself did not appear in any released game until Fallout 76.

Bugs

 * It is possible that while murdering the victim, they will wake, stand up and go hostile, however, they will still die after the murdering animation is complete. It seems that when the character being killed starts attacking the murderer, no damage will actually be dealt by them.
 * Ordinary characters killed by this perk may fall through the floor, making it difficult to loot them before they fall.
 * For unknown reasons, in some cases, the Mister Sandman animation will be replaced with the going-to-bed animation. As soon as the player character begins to lie in the bed, the NPC will begin to get out of the bed simultaneously. Upon lying down fully, the NPC will die, and the PC will immediately return to the previous crouching position.