From the Luigi up taunt GIF I made. But better quality.
This was a replacement from the pose that he is wiping his nose, because I think I felt at the time it was too close to the finger gun pose, but the connection here was that if he was wiping his nose, that could mean that he was under the weather, and if he was under the weather, you could say that he's sick, and there is no depiction of Luigi being sick more so than the game over screen of Luigi's mansion.