The tag implication #68713 spitroast -> double_penetration is pending approval.

Reason: Spitroast is a form of double penetration.

This one isn't airtight since a spitroast can include more than three partners or (more likely) have an additional form of penetration through a hand, tail, tentacle, etc., and our current definition of double penetration is exactly two penetrations.

This would be easy if we had a base multiple_penetration that was 2+, but it's currently 4+ to reduce implied tag bloat and make 4+ penetrations more searchable. I don't think it's intuitive, but I see why it was done this way.