Guardians of the Galaxy was the first Marvel Cinematic Universe film to make heroes out of a bunch of criminals. While ultimately being good guys compared to the true evils in the universe, their methods were questionable and their moralities murky. So it is no surprise that the Guardians come together after they all find themselves locked up in the same prison. There they are all given prison attire that it turns out represents their many crimes. So instead of asking 'What are you in for?' all they have to do is check out their stripes. For us however, we need a bit of translation, so here's the breakdown according to director James Gunn.
First up, we have that most vulgar of vermin, Rocket Raccoon! James Gunn explained:
Rocket's are mercenary activity, grievous bodily harm, arson (he blows up a lot of stuff), escape from prison, and, I believe, public drunkenness.
Yup, that sounds about right for Rocket. As we have seen through the first two Guardians films, the genetically-modified creature has a fair bit of self-loathing and is prone to anger due to his past. So it is no surprise that he has went full raccoon and caused grievous bodily harm or that he has drowned his sorrows publicly on more than one occasion I imagine.
Next we have the self-proclaimed, legendary outlaw Star-Lord, and the product of an unholy union between a planet and an Earth woman, Peter Quill! James Gunn said:
Quill's crimes are penny-ante robbery, grift, criminal conspiracy (from his gang involvement with the Ravagers), and having sex with members of a royal family (consensual but on some planets considered an outrageous crime for someone from his caste).
If, like me, you have never heard the term 'penny-ante', I Googled it for you, and basically it is the same thing as petty or small time. So in addition to petty robbery, Quill gets the most salacious stripe on his prison rap sheet, having sex with members of a royal family. This seems right in his wheelhouse and exactly the kind of thing he would get in trouble for, especially given his low, Terran birth. What's especially funny is that members is a plural word, so he either committed the act multiple times or once with multiple royals.
All the best cowgirls have daddy issues, and nobody has a worse father figure than the green assassin, Gamora! James Gunn continued:
Gamora keeps things simple with her long list of murders and assassinations, all at the behest of Thanos.
Gamora is probably the Guardian who has been the most reluctant in the commission of her crimes. Thanos is a scary dude and it's hard to say no, but hopefully her and adopted sis Nebula will get some revenge in Infinity War.
The next prisoner on the list is Drax the Destroyer, which is a terrible moniker if you're hoping to avoid prison time. As James Gunn put it:
And Drax's crimes are grievous bodily harm, murder, and every variety of destroying stuff you can imagine.
This is some expected stuff here for Drax, since he's like a bull in a china shop wherever he goes. It would have been funny though to see some crime stemming from his hyper literal nature, offending the wrong person perhaps.
Now you may be wondering, what about Groot, he didn't wear pants in the film? Well, according to the director, it turns out that creating CGI pants for the CGI character was prohibitive cost-wise. So to come in on budget, Groot didn't get a cool prison uniform and instead stayed in the nude. Had he been given one though, his crimes would have included mercenary activity, grievous bodily harm and escape from prison.
According to James Gunn's Facebook post outlining this cool detail, each stripe on the prison uniform pant leg represents a crime with different colors defining the category of the crime. The pattern of the stripes also gives more detail about the crime and its severity. James Gunn credits the film's costume designer, Alexandra Byrne, for coming up with the designs. The director also notes that these are merely the crimes that the Guardians have been convicted for, so no doubt there are many more that they have gotten away with.
This is part of what made the Guardians so fun and has seen what were once considered risky characters become some of the MCU's most popular. It is especially neat to see this level of detail and care put into crafting a world in a film that is part of that occasionally derided category known as blockbusters. Marvel movies are great at this, including details that 99% of people won't notice and Easter eggs that fans may not notice for years to come, all to create a more fully fleshed-out world.