With the recent and welcome addition of Girls forM, there have been a lot of works tagged anal, which only feature a male having a toy shoved up the ol' pooper.
Now I love this kinda stuff myself, but I feel it should be a seperate tag.
Sometimes you wanna see a girl take a dong in the rear.
Sometimes you wanna see a boy get his butt probed.
These are unfortunately marked under the same category, so you won't know for sure which it is until you actually read the chapter.
exhentai (Am I allowed to mention them?) has a tagging system that segregates tags between male and female; for example, a male taking it in the booty would be male:anal, or a girl stroking a tallywacker would be female:handjob.
I'm not saying this should be done for every tag, only certain ones such as anal, where I'm sure most would agree- male anal and female anal are two different ballparks.
For your consideration, I would suggest simply a Male Anal tag.
I'm sure it'd be a welcome quality of life change.