Do they say knickers in America?

Knickers are primarily used in the U.K., where it may sound a little old-fashioned or childish—a lot of British people think of knickers as what grandmothers and little girls wear (as opposed to underwear). It is often used to intentionally imply such associations or to be funny.

In the U.S., knickers were once used to refer to breeches, a kind of knee-length pants once popular for men and boys. But both the pants and the word for them are rarely used anymore.