signal
Explanation
This comic offers a Batman parody built on a simple visual pun.
The panel shows a villain (resembling the Joker) laughing maniacally -- "HAHAHAHAHAHA!" -- while standing in a beam of light surrounded by dozens of bat-signal projections in the sky. Instead of one Bat-Signal calling Batman, the entire sky is flooded with bat symbols.
The caption reads: "The best way to stop the Batsignal turned out to be Batnoise."
The joke is a play on the concepts of signal and noise from information theory. In communications, "noise" refers to random interference that drowns out a meaningful signal. If you cannot destroy the Bat-Signal, you can render it useless by flooding the sky with so many identical signals that Batman cannot determine which one is real or where the actual emergency is. This is the same principle behind jamming in electronic warfare or denial-of-service attacks in computing.
The humor works on two levels: the literal visual absurdity of a sky full of bat symbols, and the clever application of a real technical concept (signal-to-noise ratio) to the inherently silly world of comic book supervillainy.