The tag implication #51352 deep_rimming -> deep_tongue is pending approval.

Reason: deep_tongue is a little under-tagged, and I think the lack of this implication and a related one are the primary reason. "tongue used as a penetrative device" is a prerequisite to the tag in question.

Edit: I see this one's been decided previously, at https://e621.net/forum_topics/13386. I think the ones that don't fit this implication should probably be tagged differently in the first place, but it's probably not useful to keep bringing this one up so my apologies there. Deep_cunnilingus is in a similar state: https://e621.net/forum_topics/21044