What you Need
What to do
Gently drip milk off the spoon into the tea.
What colour is the drop?
You can use water instead of tea, ans you will get a slightly better view.
What may happen
You should find that a spike forms with a droplet falling off the top that is made almost entirely of milk.
The whole process is very quick so we have slowed down the process for you.
It appears that the drop spreads out forming a hole in the surface of the fluid, and then a combination of gravity and surface tension creates a wave returning to the centre which creates the spike out of about 1/3 of the original droplet.
Why does it happen?
Why does the jet sometimes form rings moving down though the liquid?
Drops hitting surfaces is a very complex subject which may scientists are studying in order to make ink jet printers that don't splatter, understand how to make pesticides stick onto plants and not just fall on the soil, and how to make surfaces which clean themselves.