Too bad he didn't leave the plastic bag on longer.

Some dim-witted robber used a clear plastic bag - you know, the kind that could suffocate you and also does nothing to hide your identity - to rob a Dunkin Donuts earlier this month in the Whitman section of South Philly.

So police are now asking the public's help to identify him.

The robbery happened at 3:30 a.m. July 6 in the Dunkin Donuts in Whitman Plaza off Oregon Avenue. The thief loitered outside for a few moments, then threw a clear plastic bag over his head, entered the store, jumped the counter and stole money from the cash box while threatening an employee with a knife.

He then removed the bag and left it behind, escaping north on foot through the parking lot towards 5th Street and Oregon Avenue. The employee was uninjured.

The robber is described as white, age 20 to 30, 6-feet tall and 170 pounds. He had dirty blonde hair and wore a ripped gray shirt, tan shorts and white sneakers. Surveillance photo caught him here.

Tipsters, call Det. Maha in South Detectives at (215) 686-3013/3014.