Does Post Malone have the most polite penis in show business?

A Page Six spy says the rapper was hanging at Baby’s All Right in Williamsburg at an after-party for a Strokes show in the early hours of Wednesday morning and needed to use the bathroom.

The VIP john was busy, so one of the owners, Donovan LaFond, showed him through a basement kitchen to a public bathroom. “He comes out a minute later and says to Donovan, ‘My penis thanks you!’ ” said the source.

Meanwhile, we’re told Malone spent the evening handing out $100 bills to any of the servers lucky enough to be waiting on his table.

“Nice guy,” said the source.