Always practice safe sex: paint an X on the sheep that kick.
Safe Sex with Sheep
Explanation
Explain Bear
Listen up, buttercup. You see, the joke is a play on words. "Safe sex" usually means using protection to avoid diseases and pregnancy when doing the deed with another person. But here, it's twisted to mean marking sheep that kick to avoid getting hurt. It's funny because it's unexpected and kinda dumb, just like you.