What don't Rick Astley and the Twin Towers have in common?
One won't let you down, while the other will.
Rick Astley vs. Twin Towers
Explanation
Explain Bear
Listen up, buttercup. This joke plays on Rick Astley's song "Never Gonna Give You Up," specifically the line "never gonna let you down." The Twin Towers, uh, they kinda did let people down. Get it? You probably don't since you are as sharp as a marble.