With Junk Flea being such a tiny map, it may be difficult to go unnoticed. However, it can be easy, but only if you know how. This will show you hiding spots, techniques, and defense strategy if you are noticed.
Doorway[]
Ascend the stairs at either site and go out the door, then run and hide behind the door. This is good for when a shooter emerges to kill your team, and you can easily stab them and get a good laugh. If noticed, run inside if its your own spawn, or find the nearest cover if not. Behind the silos or on the roof is an example.
Silos[]
Duck down behind the silos. It is recommended to stay on the outside silo to avoid grenade tosses. Take time to look back and forth, and step out to fire when the time is right.
Sharp Dead-ends[]
The tunnels can provide an excellent means of escape. Hide in the tight borders so you can go unseen, and then take out those who come by.
The Danger Zone: Behind a Barrel or a Box[]
Ducking down behind a barrel and standing to shoot is a good plan for camping, but if you are spotted, the barrel may explode from enemy fire and kill you off. Getting behind a crate is another technique. You can copy the barrel trick, and the crate will break, not explode. When it shatters, break out into a fast sprint and get out of fire's way. If you are lucky, the shooter might be on his/her last few rounds after killing the crate you were hiding behind and not have enough to kill you, but they might not, and then you are pretty much trapped, unless you run away fast enough.