Friends of P: Johnny Depp joined Willie Nelson on stage last night at the Pavilion

We guess you never know who’s gonna show up at a Willie Nelson show. On stage or off.

Last night at the Blue Hills Bank Pavilion, Nelson was joined by actor — and musician — Johnny Depp on guitar at the Blue Hills Bank Pavilion. Our spies report that he was up there for the set’s duration, and he wasn’t dressed as a pirate. Depp is currently in town shooting the Whitey Bulger flick Black Mass.

Some in the crowd had no idea it was him the entire time.

“I remember seeing Johnny Depp and thinking who’s this nerd?” one attendee told us. “Now that I’ve seen the pictures I remember it, anyway. No idea it was him at the time.”

We’re also told they played no songs by P, Depp’s short-lived ’90s alt-rock band.

According to the UK’s Daily Mail:

Johnny Depp went back to his musical roots as he joined Willie Nelson and his band at the Blue Hills Bank Pavillion in Boston on Tuesday.

The 51-year-old Pirates Of The Carribean actor was a surprise guest at the gig, with country singer Willie simply introducing his famous pal to the stage as ‘Johnny’.

Despite having an illustrious acting career that has seen him win Golden Globe and Screen Actors Guild awards, Johnny started off his career as a musician.

It is not the first time the actor has played alongside the country music legend, the talented actor performed with him at South by Southwest festival in March, and was also introduced incognito as ‘John’.

Here’s another look: