Can a pun be a sketch?

Idea for a sketch:
INT. Tube Carriage. Night.

A DRUNK MAN IS SAT IN A TUBE CARRIAGE. HE IS NOISILY EATING A TAKEAWAY MEAL. AS HE EATS HE LOOKS AROUND THE CARRIAGE. DISGUSTED FACES STARE BACK AT HIM.
AVOIDING THEIR GAZE HE BEGINS TO READ THE ADVERTS. HE FIXATES ON ONE SIGN.

CUT TO: TUBE SIGN IN CARRIAGE. IT SAYS:

"PLEASE CONSIDER OTHERS WHEN EATING"

CUT TO: OUR MAN EATING

TAKEAWAY MAN: (turning to person in seat next to him)
I'm sorry, would you like a bite of my Chimichanga?

PASSENGER: (ANNOYANCE DISSIPATES FROM FACE)
At last, I thought you'd never ask. Thank you.

PASSENGER TAKES FOOD AND TAKES A LARGE BITE.

PASSENGER:
Actually, are you going to eat all of those fries?

PASSENGER HELPS HIMSELF TO SOME MORE OF THE FOOD. SMILES.
END OF SKETCH

That's excellent! Good work.

It's well done here but often puns elicit a groan, not a laugh. Like your sketch.

Thanks for the comments, that's kinda what I was thinking... the dangers of a wandering mind on the tube...I spose what I really wanted to do was squeeze a Chimichanga into this forum, and in my own small way I have succeeded...

I think the sketch depends very much on the actors facial reaction to his stuff being scoffed. In there lies the rub me thinks.

Nice one, but drop the fries funny enough with out them.