Pictures have hit the internet of people outfitted in MAGA merch -- pictures of Donald Trump, bald eagles and American flags plastered on the chest -- and, in their hands they're holding sperm sample cups with J.D. Vance's face stickered on the front.

Next to his face, the cups read, "J.D. Vance Full Family Kit" ... basically saying the senator from Ohio has some strong swimmers -- after all, he's already got three children.

As for why these supporters are schlepping around the cups -- complete with a opaque white substance we're trying hard not to think about, just BTW -- many are pointing to Tim Walz's own issues with infertility.

If you don't know ... Walz has been very open about his struggles with infertility -- detailing how he and his wife Gwen went through extensive IVF treatments to try and have a baby after years of unsuccessful attempts.

Tim and Gwen share two kids ... a daughter named Hope -- she gave them hope after years of trying to conceive, hence the name -- and a son Gus. It seems certain Republicans think the circumstance of their conception is fair game.

Worth noting ... just last week, Donald Trump Jr. shared a photo insinuating Walz drinks horse semen -- so, it's been a super NSFW week in politics.