La Varita Mágica presents a fun gag to perform at any time.

The magician shows a kepchup boat, and points it towards a spectator.

 Suddenly, the magician squeezes the boat and you can see the sauce coming out towards the spectator's shirt to everyone's horror.

Imagine the face that the viewer will put when he thinks he is going to be stained.  

But everything is a joke and nobody is damaged or better said stained.