Trust me, I'm not stealing

Don't look on your face for ME!

For, you will only find my cousin.

Don't watch out for me in the city!

For you will find my other cousin.

Instead, maybe look in front of you,

Just fill me up and empty me continuously for the most satisfaction.

Freeze me and I may pop, yet scald me and I will be just fine.

Yes I can be small, but one of my three is big enough for YOU!

• Water's cousins are vapor and ice. I think
– Duck
Aug 8, 2018 at 17:57
• Those are cousins for sure :) Aug 8, 2018 at 18:00

Is it a

Coffee Mug

Don't look on your face for ME!

For, you will only find my cousin.

"Mug" is slang for Face

Don't watch out for me in the city!

For you will find my other cousin.

If you are in the city you can get "Mugged"

Instead, maybe look in front of you,

Just fill me up and empty me continuously for the most satisfaction.

A coffee mug is likely nearby for anyone at a PC, you fill it up multiple times a day to stay awake and satisfied.

Freeze me and I may pop, yet scald me and I will be just fine.

If you freeze a mug with liquid in it, it can burst. But they are fine to boil liquids (scald)

Yes I can be small, but one of my three is big enough for YOU!

There are three letters, and one of them is "U"

Title:

I'm not stealing is another hint at "Mugging"

• This is the correct answer. You got all the parts, so just wait for the check tomorrow :D Aug 8, 2018 at 20:56
• another thought: nyfb gur funcr bs gur unaqyr vf hfhnyyl va n h, fb gung jnl LBH pna teno vg. Aug 8, 2018 at 20:56

Could you be

Eyes?

Don't look on your face for ME!
For, you will only find my cousin.

You can only see from your eyes, so you can't look at your own face unless you are looking at a reflection. They can be a cousin because when you look at one, it looks right back at you. Also, ME could stand for My Eyes (MY EYES!!!), and a synonym for ME is I, which sounds like eye.

Don't watch out for me in the city!
For you will find my other cousin.

There are many buildings in a city, wherefore there are many windows in the city. It is said that eyes are the windows of the soul. You can also watch things go by from a window.

Instead, maybe look in front of you,
Just fill me up and empty me continuously for the most satisfaction.

In front of the word you is y which sounds like eye. In fact, the thing closest in front of you that you can see, is your nose. The nose can act as the y and the two eyes can be the e's, joining together to make eye. Also, the word you sounds like U, and the first letter after U is V which can stand for vision or view (view, sounds like VU.).

And when people's eyes get filled with tears, it can be a bit satisfying (relieving is a better word) to cry and let it all out.

Freeze me and I may pop, yet scald me and I will be just fine.
Yes I can be small, but one of my three is big enough for YOU!

Most people who daydream can have their eyes focused too much (or frozen) where they can also get a mind blank (a pop). I am unsure about the scalding part, but there are eye drops that can sting your eyes, though they are good for them, too.

Yes, eyes are small (24 mm, which is smaller than an average size gumball!) and also the word small rhymes with ball, linking to eyeball. The word eye has three letters, the letter y being big enough for the word YOU (since it contains a y).

Title:

Trust me, I'm not stealing

You can steal a glance with your eyes; sometimes you must keep a close eye on something before it is stolen; there is a pop band called Stealing Sheep which made a song called Shut Eye; some people stare into your eyes to see whether or not you are telling the truth (i.e. to be sure if they can trust you); and again, the world I in I'm sounds like eye.

• I like the creativity :D +1 Aug 9, 2018 at 13:27