Look in your pants.
Got junk? You’re a man.
No junk? You’re a woman.
Discussion closed.
If you got junk,
And you not a hunk,
Then you a punk!
Exactly! They wouldn’t even have to look. They could just reach down and feel.
Now. Perhaps you would call this a quibble, but please hear me out: please don't call sex organs "junk".
It implies that your sex organs are trivial, extraneous, or a bother. If they are garbage, that it can't be a bad idea to cut them off and throw them into the medical waste landfill.
It's body-shaming. It shows disrespect for the physical indicators of man and woman, masculine and feminine, and reinforces the whole gender dysphoria madness.
OTOH, if you don't want to use the textbook names, IMHO "wedding tackle" is kinda fun (i.e. "the equipment you need for your wedding") -- and I used to remind my little boys not to let anyone hit them in the groin, and to protect their "family jewels."