I went to a museum of contemporary art. A man with a hard boner exposed was lying on a conveyor belt. The dick was dressed in the costume of a medieval paladin. Then the conveyor belt started moving. Heavy rains and blizzards blew against the paladin, but he never went down.

After a while monsters appeared. As the man on the belt shook his hips violently, the paladin swung his sword savagely and beat them in a flash. The conveyor keeps running. He crossed over hills and deep dales, eventually defeated the evil king and rescued the damsel in distress.

That was the dream I had on the night of my 50th birthday. For real... Anyway, HBD to me! It might also mean Hard Boner Dream to me.