Well, before you come up with a serious app idea, it could be a good idea to explore some less serious ideas;

- Dating app for pets

- Mobile game of guess the colour code

- Social network for babies

Weird ideas like these are fun to make, can go viral and get you noticed as a developer... [1] Some inspiration for you.

[1] https://play.google.com/store/apps/details?id=com.jacquessmu...