for the male genitals
Most likely the "wedding" component refers to the sweetly anachronistic notion that men and women would have no need of their groinal pleasure packages until after marriage.
The second element...well, probably a nod to the denotation of "tackle" as "equipment used in a sport or occupation".
Not the most flattering turn of phrase, I'll admit, but once deciphered, an amusing clarity of purpose does shine through.
Try not to use it with your drinking buddies. They may look at you funny and refuse to take you fishing ever again.