When a straight male encounters another straight male, usually a friend, under the mistletoe and non-sexually kisses them in line with the Christmas tradition.
Art that tries to be highbrow, but really isn't. Status-seeking middle class people buy middlebrow work to display, not to enjoy. Writer Virginia Woolfe famously decried middlebrow as "a sticky slime of calves-foot jelly", though her work could be classified as middlebrow too. Still, as long as you actually read the books you buy instead of just using them to set of the furniture, who cares?
My family library is so middlebrow: all leather-bound editions of the Great Works. Still, I enjoyed looking at the pictures as a kid.
Most people think of mistletoe as being romantic, but it isn’t, not really. The name derives from mistletan, which means a twig of mistle; the seeds of the plant are propagated through the excrement of birds, notably the mistle thrush. If you now take account that the old Germanic word ‘mist’ means shit or dung, mistletoe’s name translates as ‘shit plant’.