This was posted by Herb MacNaughton in Pun American Newsletter. From there, it ended up on the groaners listserv. The original author is not known.

The longshoremen were about to vote on a new contract which was unacceptable to most of them. However, Mike indicated that he planned to support it. On voting day, he showed up with a black eye and bruises.

“So which way are you going to vote now, Mike?” taunted his buddies.

“Well,” conceded Mike, . . . “I guess I’m going to have to give in to pier pressure!”