Pico uses the stretch-and-touch method. He puts his front paws on our chair and then streeettchhes his back and, as he does, his paws just barely touch our thighs and when we look at him he gets that totally innocent look "I was just stretching!"
Then there is the little sound of annoyance and impatience when he goes "erk" if his treats are coming fast or often enough when my husband is eating lunch. (I don't share with him but my husband does.....pieces of veggie or bits of toast)
He also has a certain place that he will sit and stare at us when he has to poop. My husband calls it the Poop Place and he'll call to me in the other room "Your dog has to go out" and Pico will then run into my room and stand there and cock his head at me like "Hey! SOMEBODY take me out......"