My family has redefined "prank" to mean "a surprise nice gesture you do for someone". So for example: sneaking out early in the morning to buy donuts for the whole family, or doing a household chore that's usually someone else's responsibility, or hiding a package of someone's favorite candy where they will find it unexpectedly. The key is that it is something that you know the prank recipient will be not just surprised but also happy about. I highly recommend this approach, it makes April Fool's Day much more fun imo