General solution for any app including iFunny when it crashes is the following. Try these and I’m sure that it might work. It might be due to bugs or temporary glitches.
Try turning off the WiFi or data connection and then turning it on again. In other case, you can even connect to another WiFi network.
Log out of your iFunny account and then log in again and check whether it is working. You would have to close the app completely and check.
Now, uninstall and reinstall the app, it will work for sure.