A tongue-twister is a phrase that is designed to be difficult to speak properly.
Usually tongue-twisters rely on similar but distinct phonemes (e.g. s and sh), unfamiliar constructs, or other features of a language.
Tongue Twisters, amazing fun with friends and family
Tongue Twister of the Day
Three sweet switched Swiss witches watch three washed Swiss witch Swatch watch switches. Which sweet switched Swiss witch watches which washed Swiss witch Swatch watch switch?