distorting mirror

Short definition from Wiktionary

Noun

1. 1
   A curved mirror, often using convex and concave sections to achieve a distorted effect, as: With strong effect, as a popular attraction at carnivals and fairs: synonym of funhouse mirror.
2. 2
   A curved mirror, often using convex and concave sections to achieve a distorted effect, as: With subtle effect, to mislead customers in clothing shops: synonym of skinny mirror.