It's pretty common to launch from the starter stations to see cargo cans floating in space labelled 'Free Ammo' - take a look at their colour on the overview, if they're yellow then they're a trap. If you pick up anything from a can which is yellow then it's considered 'stealing' from the can's owner, as such Law Enforcement gives the owner, and possibly everyone in his corporation, the right to shoot the thief without interference. As such, PVP noobs will place these bait cannisters in space and hope that some clueless noob 'steals' from them, so that they can shoot the perpetrator and get a kill. Just in case you're unsure, eve will warn you when you're trying to take something that belongs to another player.
If the cans are Blue or White then it's ok to take things from them without being branded as a thief.