knotting is when the bulbus glandis expands inside to prevent semen from escaping during mating, it's the section of erectile tissue that's typically towards the base of the penis, just above the balls in canines but it can vary in size and length. Though for anyone that either has never seen their dog do it irl or had a vet explain it to you I can see why you'd think it had to do with the balls being inserted. (I've also read a few ao3 fics that have explained it in detail before)
the way i've been reading bl for 6 years with the WRONG mental image... but thank you for the lesson lmaoo what a nice topic i learned today
I hope this sends as the right page https://www.mangago.me/read-manga/boku_no_high_spec_kareshi_sama/mf/iur_chapter-5/pg-30/ but in this manga they show it more uncensored, tbh from the lightsaber in Mind The Gap they kinda make it seem exaggerated. irl it's more like two small inflated balloons above the balls
In my 6 years of reading bl, this is my first time seeing knotted alpha dihh, i thought knotted is like their balls also inside the hole and thats why they cannot pull it immediately after knotted