Whats the funniest transformation you've seen in a manga or anime.?

Manga and anime is full of moments where because of the monser of the week, a spell gone wrong or a new invention the main characters turn into something hillarious. I've seen them turn into animals, inflate like balloons,get younger or older, swap bodies and even turn into sumo wreastlers. So what anime or manga TF have you seen that was just LOL.