A silly expression seemingly invented by two languid stoners who had smoked themselves beyond the point of retardation. Usually sung in a non-harmonic fashion by two people that can't sing and probably never should. Quite entertaining if the selected parties are beyond cheeched. Yeah... That's right. It's the face machine.
Later decided that marijuana itself could be the face machine as it gets you faced and it prompts such undeveloped thought patterns if consumed in high enough doses.
Person 1: "Said I'm talkin bout the face machine!!!
Person 2: Face machine! Awww yeah. Talking bout the fuckin face machine.
Wash, rinse, repeat.