The Assassin’s Teapot is a way one could achieve such a ruse, allowing two different liquids to be poured from what is seemingly a regular teapot, as shown by [Steve Mould]. (Video after the break.) ...

Teapots are not just for pouring tea; some have surprising features that can perform tricks. One fascinating example is the “two-heart pot”, also known as the “assassin’s teapot”.