That’s what it should be called, lest vaginal sex be called “labial sex”. Just a thought.
I approve the thought. Well said. And what about “lip service” while we’re at it?
If you use just the word of the orifice, then that would make goat sex just be vaginal/rectal sex as well; the whole goat part would be completely lost!
Not that this effects me in any way… Just sayin. 
Obviously you seem to be concerned with defining sex by the place where the head of the penis is doing it’s stuff. Since the rectum is only about 20cm long well endowed men would then be performing descending colonic sex.
Colon-opulation.
“Rectal sex” just sounds sexier than “anal sex.”
“Anal sex” would be better used to describe some ridiculously specific fetish scenario where someone just can’t get off unless everything’s perfect. Royal blue 5/8" garters left on for exactly 17.8 seconds, because 3/4" sky blue garters left on for only 12.7 seconds will ruin the moment.
“Rectal sex” sounds like a yet undiscovered dinosaur.
It does, doesn’t it? If you spin it around you could get Sectal Rex which might have something to do with the king of a religious offshoot. Maybe one of those floats at Mardi Gras.
Not sure it’s going to look any classier written on a Valentine’s Day card, though.
How do I love thee? Let me count the ways.
I love thee to the depth and breadth and height
Your rectum can reach.
Happy Valentine’s Day
Your mystery admirer
Roses are red
Violets are blue
Your rectum is scrumptious
Now bend over, do.
It got called that over here, in HIV educational adverts, but only because TPTB felt unable to come out and say “anal intercourse” along with the rest of us.
Of course “anal intercourse” could just mean talking through your @hole 
Or even just a pedantic conversation.
To be fair, for that scenario you’d have to specify “anal retentive sex”, otherwise someone might think you meant anal expulsive sex, which is crap most people wouldn’t want to deal with.
Y’know, that’s what Senator Santorum always said, too.
Sounds like a boxer.
Annnnnnnd in this corrrrrrrnerrrrrrr.
Weighing in at 215#
Recccccccccccctallllllllllllllll SEX!
Ding, ding.
I just love Tony Soprano’s name for the senator: Sanatorium.
Let’s get ready to rrrrruuummmm-bbbbuuuuuuuullll!
Undiscovered Dinosaur. Hmmm.
Many years ago attended a feminist art show. One painting was entitled "Clitoris Rex:, and showed what apparently a T. Rex with a VERY odd face confronting a man.
I just Googled “Clitoris Rex” to see what came up.
This did. Times has changed:
Actuallly, the best part of “rectal intercourse” is the wide eyed expression on the woman as it goes in! 