I took a crocodilians class at the Critchlow Alligator Sanctuary in Athens MI, and the owner trains his alligators to voice commands like that. There's a video of him on his website with his gator that he rescued and raised, Godzilla.
One of the guys that works there with the three footers got into their pen and sat and called them, and these little gators climbed right up into his lap, laid their heads up on his shoulders and legs like house cats. I got to work with the eight footers, and it takes some steeling to be able to walk right up and pat one on the back.
There's no doubt that alligators and crocodiles (especially crocodiles) can REALLY ruin your day if they wanted to, but then again so can dogs and even cats. It's all based on the animal's attitude and the way you behave around them.