Backrub chains appear frequently at youth groups and bible camps. Whenever pubescent* Christians of mixed gender are gathered to study the Bible or worship, the likelihood that a backrub chain will form is increased tenfold.
Very popular with singles groups and college ministries. People who aren’t Christians love Cheesy Christmas Sweater Parties too. Maybe it’s one of the areas where the two cultures intersect. Although at a Christian culture party there won’t be any alcohol, that’s for dang sure.