I have seen these all over Pinterest and I finally made myself one. This is a cute little trash can that cost me $2 from Goodwill. Here is how I did it:
Apply painters tape to the outside to create stripes or polka dots
Spray Paint and clear coat to seal the paint
Take a Carpenter's knife and run it down the sides of the tape to ensure the tape comes off cleanly. If you skip this step, You won't have perfect stripes or dots.
And you're done!