How to make a funy surprise on 1 April for boring parents?????

SURPRISE________It is possible to prepare a banal trick, for example to pour in salt tea, in a tube from paste to pour medical or something else. But it is also possible to prepare serious tricks, for example over a door to suspend a bucket with some liquid and to carry out a thread what at an entrance of the person it would touch a thread and on him the bucket with paint has poured out. There is an option shampoo to replace with color paint, will be ridiculous, but a little problemno. Somehow so.