April 4th (4/4) is International Rock Beat Day. A "rock beat" or "common time" is four beats per measure of music, the standard rhythm of most popular western music.
"We've got to play some Beatles records on April 4th... it's International Rock Beat Day!"
If someone goes for a pound and you go for a high 5 and cover their fist, you say "paper beats rock." If done intentionally this should be considered a diss worse than to leave hanging.
He tried to pound it so I went for a paperbeats rock. He was so embarrassed, he had to leave the party.