Terrence, the terrible cairn terrier (RIP), did a LOT of strange things. Probably the strangest was his excellent visual acuity...he watched the bugs land in the waterfall pond at the apartment complex where I lived and would bark at them. They would jump, land again and the tiny ripples seemed to be visable (esp. in reflections) so he'd bark again...and on and on

I'd have to take him inside to stop him. But then he'd see reflections inside (there was a pond and I lived in a basement suite and start over

He was a real character but then both of my cairns were.