Depends

on if the day is belonging to the single people or whether it is a description of the day itself. If the day 'belongs' to the single people then it's "National Singles' Day" and if it's a description then it would be "National Singles Day". I suspect either would be acceptable grammar as the day could be seen as belonging to single people but given the occasion I would suspect the latter would be more correct.

Posted By: Capital Canary, May 1, 07:09:57