They're crushing the candy and inhaling it, in videos seen all over YouTube.
The motivation behind the crushing and snorting of Smarties isn't known.
The bizarre trend is happening across the nation, including at a Rhode Island middle school, where the principal sent an email about it to students.
And a health expert is warning about the dangers.
"Anytime you snort or inhale a substance into your lungs that is not meant to be it is definitely hazardous to your health and could have significant health consequences for individuals," said behavioral care expert Rebecca Boss.
Some of the negative side effects of snorting Smarties include infection and scarring of the nasal cavity.