This is what's happening:William Fleming said:My puggle (pug and beagle crossbreed) often has her bottom row of teeth showing after shaking her head (you know the gesture that dogs do). It's like her teeth get stuck outside her mouth. Often though when she knows she has been bad and told off she will go away and comeback a minute or so later with her bottom teeth showing (it has happened too many times to be a coincidence meaning... she has most likely practised and can basically do it at will now).

My sister has 2 Jack Russells, one of them is a "mini" (kind of looks like a large Chihuahua more then a Jack Russell).
Lady, the regular Jack Russell, has some funny quirks. One in particular is really cute. She has this weird reaction to sneezes. If you sneeze around her, by the time your done recoiling she'll be up in your face. We have no idea why she does this, she'll even run from one room to the other to catch the sneezer in the act. Having allergies around her can be a hassle, but she gets so excited over it... it's just too adorable.
Shylo, the mini, has another weird one... he likes to slap people in the face. Sometimes you'll just be minding your own business when the little bugger will dash straight to your face and paw it a few times. It's funny to look at, as you he'll raise his paw as high as he can get it and just plops on your face (usually your mouth or cheek). If you try to hold him back he'll just alternate paws or shimmy his way out of your grip and continue pawing. It's not a prelude to anything, he isn't trying to get you up or make you do something, he's just pawing your for the sake of it.
The reason why he does it is his owner likes to play fight with him when he's on his chest. This usually involves just clasping his snout with his palm and goading him into pawing him back. Now that's how he treats everyone. It's totally harmless as he never scratches, just slaps you with the paw (and he doesn't have the force to hurt you).
My old pet, a Maltese Terrier called Ricky, had it's own quirk. He OWNED the couch next to my Mom, to the point where he would growl at anyone who would dare to sit next to her. This included my Dad. That never changed in all the years we had him.
Also, when he was old he became forgetful. He would prefer his own company in his own bed for most of the day, but would always "check in" on my mom, who was either in the kitchen or in the living room. He'd do this every half hour all day long. It was adorable, but sad at the same time as he was getting so old he would just forget what he had done.
He also LOVED grapes, though they did not agree with his digestion. I mean, it was like crack to him.