All three of my dogs do the butt in the air thing, this is doggy body language for lets play! Both Mika and Nikki(staff bull terrier) use their paws in play and lick ALOT I think both of these traits are terrier things
They both steal/hide things and lift their front paw when cautious too-more terrier traits! Mika is the only one that climbs on the back of the couch (thank goodness the other 2 are far too big
) And both Mika and Nikki are bouncers lol, they will jump up and down for attention or at the fence if someone goes by and Nikki can leap over any baby gate and even over the extra high doggy gate (but she doesn't do this often 'cos she knows she will get shouted at) oh and they both sulk too if they are told off! I esp. love the way Mika bunny hops through long grass (Nikki does this also) its sooo cute. All in all I'd say yorkies are typical terriers or should that be terrors lol, Mika and Nikki are sooo alike in many ways even though they look so different.