I loved this trait in The Sims 3 and couldn't wait to try it out now.
The option to swipe something is active anytime of the day, not just at night like it was in Sims 3 and you click on the item you want to take instead of the floor and them taking something at random.
The option resets after 4 hours and when it is available if you leave your sim alone it don't take long from them to swipe something on their own. They really like to steal.
There's two new chat items available that I've noticed. Under Mischief you can Ask about prized possessions and under Friendly there's Enthuse about thrill of the steal.
Some items you can't take are toys, beds, dressers, bathroom items (toilet, shower,etc) cooking items (stove, fridge, counters, grill) skill items (easel, woodworking bench and workout equipment) but you can take musical instruments. You can't take a table but you can the chairs around it. Items have to be on the active lot, you can't take items around the neighborhood.
Some items you can take are electronic items, decor items, outdoor plants like flowers and bushes but not trees, chairs and couches.
Edit: Forgot to add when they swipe something they get the moodlet of Exhilaration Steal, Energized +1 for 4 hours.
I haven't found out what happens if they get caught yet. My sim has a mischief of 8 and stole a TV while 2 people where watching it without getting caught.
I'll have to try it with a new sim and see what happens.
Edit again. Made a new sim and when you got caught he got a moodlet of Got Caught, Embarrassed +2 for 8 hours
And with out any mischief skill the only thing he could try to take in the Landgraab house was small decor items or table lamps. So I guess the higher your mischief skill the better the items you can try to swipe.