I'm thinking of making a fake pregnancy post on April 1st
Why would you joke about being pregnant? You know that so many people struggle with fertility.
I'm sending them a lot of fake photos of a positive result on a home pregnancy kit.
Are you sure that your friends are going to find this funny?
It's a prank to scare them. They have to be scared of something and it might as well be a fake pregnancy test.
I get that you are trying to just lighten the mood and get some laughs, but this is not something to joke about. It is not a good idea to lie about pregnancy.