A mashup is like when you mix and match your toy cars and make a new one that's totally cool. But instead of toys, it's music. It's when someone takes different songs and puts them together to make a whole new song. Do you know how you can take your blue car and your red car and stack them up to make a super long car? That's kind of like a mashup too. The person who makes the mashup takes tiny parts from different songs and puts them together to make one big song. It can be tricky because they have to make sure the different parts all fit together and sound good. But when it's done right, a mashup can be really fun to listen to!