Green Day's Billie Joe Armstrong Acknowledges 'September' Joke

It's that time of the year again -- when everyone makes jokes about Billie Joe Armstrong ... and he's totally in on it, despite how difficult of a time this is in reality.

The Green Day frontman tried to get ahead of all the memes and posts that inevitably were posted anyway -- taking to the GD Instagram account to throw up a photo of himself floating on a giant rubber ducky with a drink in hand.

His caption is pretty simple ... "GOOD MORNING. YOU’RE WELCOME." BJA noted that he's in Singapore right now, and it seems he's on a bit of vacay -- which is also telling.

What we're talking about, of course, is his band's famous song "Wake Me Up When September Ends" ... and all the cracks that are online right now, making fun of the fact that Billie must be rising from his month-long slumber on October 1st.

It's all in good fun -- at least on the surface anyway. The problem, though, is that there's a bit of a dark origin story to that classic ditty ... and it has to do with Billie's father and him passing away when he was a young boy, back in September of '82 to be exact.

This is well-chronicled ... as BJA has gone on record many times over the years to explain this, noting that the song is about him dealing with a hard time in his life and having to process the death anniversary of his father -- which he did through this song.

Seems like most people are simply unaware of this hard truth -- which is fine, but going forward -- folks should probably chill on the Billie jokes every October 1st ... 'cause like we said, it's actually a sore subject for the guy. Although he's clowning around here, it's gotta be tough.