The purpose of a p trap is to stop sewage gases from getting into your drain pipes. We like to have garbage disposals/dishwashers in our area p-trapped as the same plumbing services both.

Under the sink 'u' to stop sewer gases. 

Are you asking this question on purpose?

This is my guess:

Minimalize the stink!

Now you're just being silly ;)

A device under a sink to prevent sewer gases from escaping and competing with me!

P traps are part of the plumbing.  

The other pee trap is when you are on a long road trip and there are no McDonalds within 100 miles. 

It's a curved pipe under the sink that traps your

"Pearl earings" or the

"Personal belongings, when they go down the drain. You will be able to

"Pluck" them out, before they end up in the

 Public Sewer.

 Phew!

AKA Cesspool

Guess I am late to the P-party.  As you Tony and Suzanne Marriott, Associate Brokers would say many comments NAILED the correct answer.

it's under sinks .... traps debris.... prevents sewer gases from backing into the home.... 

Tony and Suzanne Marriott, Associate Brokers A "P Trap" is the drain pipe under the sink shaped like the letter "P". It prevents sewer gases from backing up into the house. Also, where you may find that valuable piece of jewelry dropped down the sink.

You received some good response.

I know this one.

In most homes, there is a P-trap installed under the sinks in the bathroom and kitchens. A P-trap is a plumbing fixture that has several purposes. It traps debris that has drained from the sink and prevents it from forming a clog deep within the plumbing system, and to stops sewer gases from passing into the home. 

Lots of great answers already.

I see you have received the right answer!

The U shaped pipe under the sink.

The trap under a sink.

I know this one. That's a U joint under your sink to keep the sewer gases from getting into the house. If it dries out you will get a bad smell in the house. 

I am not even going there! What about the S Trap?

Even I know that one

Could it be a trap for P's.

In drains (sink, toilet, shower) to help stop sewer gasses from coming up.

Its not a urinal, though it is common in every bathroom, and kitchen.

One better call 911 right now if it is a truly a trap

Under the sink.  Stops sewer gas, and enables clogs.

Drainage to keep cockroaches and odor away from sink.

It is used to trap "Pee".

Using words that start with P too much !

Isn't that pipe loop under the sink? Or is that where bums go to relieve themselves?