Subvertising is like when you play pretend with your toys and you make up a silly story. But instead of toys, it's about ads that you see everywhere like on billboards, TV, or the internet. Subvertising is changing or making fun of these ads to show something different that might be funny or serious. This can be done by adding words, pictures or even drawing on the ad to make it look different. People sometimes do this to make fun of the ad or to make a point about something important. It's a way of expressing yourself and making people think about what they see in advertisements.