One of the best dogs I had was when I was in my late teens/early 20s. He was a mutt, we think probably a Sheltie/Min Greyhound mix, had the coloring of a sheltie but was shorthaired. Smart dog.

Our back doorbell had fallen off and we hadn't gotten around to fixing it. The dog figured out that if he pressed the two wires together something would happen.  We had a houseful of company one holiday and a cousin asked if they should let the dog in. We told them he'd ring the doorbell. And of course they didn't believe us!

Ten minutes later ... "DING DONG!"  I told the cousin, "It's the dog."  Sure enough ............

Love pets. Couldn't have them for so long (apartment living), now making up for it. Four dogs, two cats, and a bird.