1-Methylcyclopropene

Is the interest here that the molecule has a double bond in a three-membered ring?

It's pretty strained but far from the weirdest cyclic systems.

There are some cycloallenes with two sequential double bonds,

https://pubs.rsc.org/en/content/articlelanding/2015/qo/c5qo0...

You can also get triple bonds in a large enough ring

https://en.m.wikipedia.org/wiki/Cycloalkyne