At least, that's what I made out of, but I welcome a proper explanation from a native speaker!
We've got "to get a hard on for" (or, "to get wet for") used for "likes very much", in "low" English registers. A bit less politely, perhaps (I don't have a read on exactly how offensive this usage is? If it is at all?) "to be gay for", as in "Tim's gay for Zelda games" is somewhat common. May have originated with or been popularized by South Park? Not sure. Though, unlike "sexy", none of those are common in business outside incredibly-brotastic environments.
At the same time in Dutch, we use it also, exactly the same word "Geil" with exactly the same sexual meaning, but for us it has a bit of a dirty feeling.
I had conversation with Germans: "oh that means horny for us", they: "yeah for us too".
As well as I find Horny in itself a bit more invasive then sexy.
I'm not even sure where its from. Probably some comedian.
Tina, was kosten die kondome? Tina replies: 3,99. To which a customer says: Nein, 2,99, sie sind in Sonderausverkauf.
My extremely limited German translates "gespart" to "saved", and "Wochen" to "weeks". I'm guessing that the two liner actually translates into something like "Have you come? / Weeks ago", but I'm having trouble wrapping my head around it.
With regard to the other quote: a man cannot save sperm for weeks, he'll have a wet dream eventually, after approx one week. So its either a straight up lie, an overstatement / white lie, someone who doesn't know such (though we don't know if the person asking knows such or sees through it), or its taken honestly and literally (he's saved up, but who knows how full the bucket is). Since we both have autism, I suppose we go for the last explanation.
Edit: idiom
Gesellig is also used for occasions, like a geselliger Abend as also listed on the Leo link. In Switzerland it's sometimes also used for places like a geselliges Restaurant. From that perspective I use the German word in pretty much the same way.
Side note: The adjective likely comes from "Gesellschaft," which can mean "society" but also "company."
In Bavaria and probably the rest of (Southern?) Germany as well. I doubt there's much difference between the German and Dutch words.