Klein posted the cryptic picture on his Facebook profile yesterday, showing Prince side-by-side with an old photo of Klein when he was younger -- presumably to show the resemblance.
Under the photo, Klein wrote the caption, "hmmmmm" -- a wink at people who've been saying for years that Klein provided the sperm that fathered Prince and Paris.
You'll recall, Michael Jackson's ex-wife Debbie Rowe gave birth to Prince in 1997, and daughter Paris the year after. MJ's third child Blanket was born to an anonymous surrogate in 2002.
Arnie has previously denied being the dad, telling Diane Sawyer, "To the best of my knowledge, I am not the father of these children."
So we gotta ask ...