Typically the joke is that you escape family on Thanksgiving with your cousins to go on a walk and get high before returning. This twists it and adds incest

They appear to be from Birmingham.

Not the UK one.

Sure! Thanksgiving is principally a national holiday in the U.S. that traces its roots to religious and historical traditions from England, particularly during the early 17th century colonies in the New World.

It’s meant to be an autumn harvest holiday. The apocryphal story is that Puritans sat down with Native Americans to feast and celebrate goodwill between their respective groups but the evidence for this is suspect at best.

Over time, Thanksgiving became more popular and involves heavy travel during the (pre-) holiday season. It’s a chance for families to enjoy each others’ company before Christmas and feast on roast turkey and a variety of vegetable dishes.

Hope this helps! Go with God.