Little Timmy is a joke that has to do with something bad that it looks like a kid made it, like for example. A bad song that sounds like a little kid made it. Little Timmy is used a term refering to stuff that looks like a little kid made.
…And the teacher a trump fan asked Little Timmy “if your dad was a moron and your mom was an idiot then what would you be?” Little Timmy: “a trump fan”