MacGuffin

The MacGuffins are a puzzle of sorts that Watchers give to their Slayers to test their skills. Fearing that Buffy was out of practice, Giles made a bet with the MacGuffins that she could still beat the record of a previous Slayer that the MacGuffins faced centuries earlier. After they wreaked havoc and trashed her father's house, Buffy made them passive by slamming them into each other, which caused teh MacGuffins to interlock. When they told her that Giles bet on her, Buffy sent the MacGuffins back to his house to get even.The MacGuffins are immortal and are incapable of being harmed.Their only handicap is that they cannot touch each other without interlocking.