While not strictly a way of getting past them without them going off, per se, there is another way to get merchandise out of the store without being questioned. The alarm sounds when something passes through the gates that hasn't had it's "strip" deactivated, right?. So that means if you didn't pay an item it, the alarm will go off.
So what if the alarm went off for everyone regardless? It would be completely useless.
Most older gates (newer one, I'm not sure of) work (in basic terms) by having a tuned electrical field maintained between two nodes. The metal 'honour strip' in the item has been imbued with a property that interrupts that field in such a way that can be detected. Simple, right?
Here's where the interesting part comes in. Many (older) security gates are quite sensitive; this is why keys and cell-phones can set them off. One day an old friend of mine were reasoning that, if the gate detects these strips, it might do it on the basis of magnetic fields.
What we did is get a very large iron plate (perhaps 9 inches by 18 inches) and wrapped it with wire, then lashed it to my friends back. It hooked the ends of the wire through a toggle switch and then to a power source, in this case 3 12v lantern batteries in series.
I probably don't have to explain what it was, but I will anyway: we constructed a what amounted to be a huge wearable electromagnet. And so, wearing our gear, we went to try it out at a department store.
The first time we tried it, we were about 5 meters from a gate. Flip the switch for 5 seconds. Nothing. Second time, though, about 3 meters (~ 10 feet) from the gate we did indeed bring forth music. A quick 1 second toggle was all it took to set the gate blaring, interrupting it's delicate magnetic field. Knowing we had this power, the practical upshot of it is we triggered the gate a few unsuspecting people, who where later found to not be carrying anything stolen at all. So, after about about 4 occurences of innocent people being fingered, the store manager has a word with his floorwalkers, and decided to turn that gate off for the day until a serviceman could check it out.
That's one way to get past it. There is a problem, however, because it happens to be a huge magnet is will probably permanently damage any TVs in your immediate area. C'est la Vie.