Simple question. Simple answer.
'Drop', in this context, means to unleash, expel, shoot out.
'A', in this context, refers to something for the first time Ex "a horse, a cookbook, a hammer."
'Wad', in this context, means semen, cum, jizz, ejaculate.
When we combine it all we see that "drop a wad means":
Unload jizz. Expel semen. Shoot out cum.
Let's use it in a sentence:
Every time I drop a wad I carefully clean up after myself with a tissue.
And now in dialogue:
Guy: I am so hot for you I could drop a wad just looking at your naked body.
Girl: Well that's sweet and all, but I'd like to have sex and for more than 90 seconds.
Guy: OK, well what should I do?
Girl: Why don't you drop a wad first and get it out of your system. Then we can have sex right after and it will likely prolong the next time your body needs to again, drop a wad. Cool?
Guy: Cool. I'll go to the bathroom and quickly drop a wad. Thanks, Stacey, good idea.
Funny Guy
OMG! Love the dialog example...lmao. Thanks. I needed a good laugh today:)
With respect to my revered collegue, it can also mean "Spend a ton of Cash." Otherwise, dropping a wad on number 10 in the 3:30 at Pontefract goes way beyond disgusting .....