ass has been aliased to anus, so *_in_ass should be aliased to *_in_anus.
Main thing is I just want consistency. Currently, there are some tags that use _in_anus and some that use _in_ass. That leads to mistags.
For the reverse BUR (with discussion), see topic #38479. I don't really care which of these go through, but at least one of them should.
I will only be covering tags with 10+ uses here, since there are so many *_in_ass tags that have only been used a few times. Those can be moved over without an alias.
I also haven't done a large BUR before with implications, so might make some mistakes here.