The heroes are on the ropes, the Evil Overlord has been awakened from his ancient slumber and his kung fu is stronger than theirs. While the heroes are licking their wounds, they wonder what unspeakable evil he's plotting, and the camera makes a cut to...(Dramatic Pause!)...the villain trying out some jeans and T-shirts at Hot Topic.
Similar to a Gilligan Cut with a villain as the Gilligan, Villains Out Shopping is a humorous cut to the villain doing or enjoying a perfectly mundane hobby unrelated to torture or being evil in general, sometimes in an absurdly dramatic or menacing manner for extra funny. Occasionally, the hero will join in and go Go-Karting with Bowser, and they generally won't attack villains during such activities, if only due to the market being a Truce Zone.
A similar situation is one where the hero has mistakenly concluded that one of the usual villains has committed a crime, when really, it was a different one. The hero will knock down the villain's door to discover... them trying on leather pants. Like we said, a crime.
Generally used to humanize the villain, who, more often than not, is Affably Evil and/or a Punch-Clock Villain; as such, do not expect the Complete Monster to engage in this, except perhaps to subvert it (however, even they can do this without subverting it, since they can have also harmless interests and know how to blend in).
If someone makes the argument that the villain's actions prove shopping is evil, they're committing the Hitler Ate Sugar fallacy.
See also Welcome to Evil Mart, which is an establishment that caters specifically to villains who have off-time. Kingpin in His Gym and Mob-Boss Suit Fitting are subversions, as the villains may initially seem to be enjoying some downtime but are actually training for/planning further villainy. Not Me This Time may occur if the heroes attack the villain because they didn't anticipate a shopping trip. A fanfic about the shopping trip is a Curtain Fic.
Note that this is an Omnipresent Trope for many Villain Protagonists, especially in interactive media where they are given options to shop around.
For the heroic version, see Heroes Gone Fishing. See also Villains Love Entertainment, which overlaps significantly with this trope.
