I want to message my crush via a fake instagram account.
What's your reasoning for doing that?
Because I think that this could be fun.
That doesn't seem very nice though. You should not lie to others, especially people that you are fond of.
Wah, what do you know anyway. I don't need your advice.
It's ultimately your choice whether to listen to my advice or not, but it's wrong to lie to and deceive others. If you want to get closer to your crush you need to do so in a way that is based in honesty.