who is this old boy and what is the film?

[Rod Serling]

a clip shown on film night about 10 years ago. the scene shown has an old seasoned character actor (american), being bored the pants off by some young guy. old boy keeps dropping off, and eventually stares with eyes wide open, then threatens the kid if he don't shut up he will kill him (in a tongue-in-cheek, but angry, way).

come on guys, it's really bugging me!