What does the American expression "Bring me/pick me up a t-shirt" mean?

[Valso]

On some tv shows, like "The 400" and "Stargate SG-1" and quite a few others, sometimes the characters say this phrase "Bring me a t-shirt" or "Pick me up a t-shirt". Since none of the characters look like t-shirt guys, I assume that's some kind of an American idiom that I'm not familliar with. Both Google and DuckDuckGo didn't understand my question which was pretty simple ("American idioms"+"pick me up a t-shirt"+meaning) and so they didn't show me any possible meaning.
I know what each of these words mean by themselves, after all I learned English almost 20 years and I'm watching everything American without any subtitles or vocal translation, but I don't know what these expressions mean in contexts which have nothing to do with clothes. Like on "Stargate SG-1" on one of the episodes Col. O'Neill was giving orders to his men to hold the position and one of them saluted him and said "pick me up a t-shirt".

Updates

+1 y

I'm tired and I've "eaten" some characters, LOL I meant "The 4400", not "The 400".

[MTC29]

Having never seen either of these TV shows it is impossible for me to understand the context.

Even so, there are expressions such as "Been there, done that... got the T-shirt."

Because T-shirts are often awarded for participation in contests or events, getting the t-shirt means that you've already done/accomplished that specific task.

After Col. O'Neill gave the order to hold the position, did he give the appearance heading back to headquarters or the safety of a bunker? If either were the case, then "Pick me up a T-shirt" is a smart assed comment indicating that the leader is returning to relative safety, while his men were left to hold the line/position.

[Valso]

I see. Well, it looks like someone has uploaded this particular scene on YouTube, so you can see it here, it's in the first 40 seconds of the video, so no need to watch the whole 3:39 min video.

https://www.youtube.com/watch?v=dsRRenNE6Yk

[MTC29]

Sort of what I thought: a smart-ass comment from a guy left out in the field while his CO (commanding officer) goes to the "rear with the gear," which means returning to relative safety where the equipment is stored.

[Valso]

Actually, he didn't go to safety. He went (with the rest of SG-1) to rescue the abducted by the aliens USAF officer. The one left at safety was actually the guy with the smart-ass comment. :) I'm guessing he said that comment in disappointment he'd miss all the action.

But still - thank you for the clarification on what the expression means. :)
There are some American expressions that not even Google can translate. For instance, I've played the Hard Truck games (by SCS Software) for years but it was only recently when I finally was able to understand what a phrase from it meant. On that game there's a sort of a CB radio and the AI drivers talk to each other. One of the phrases was something like (I don't remember it exactly) "There's a croc going in the granny lane". I don't remember whether the first word was "croc" exactly but it was something about an animal. And it took me years to finally understand that "granny lane" meant the slow lane or the most right lane which is meant for slow vehicles such as trucks. 🤣

[IsoUser]

I couldn't honestly tell you, but I am essentially 18 years out of sync serving in US Military in the Middle East LMFAO