Ah hahahaha... #5. It reminds me of my bud's Airedale. He'd play with pebbles, then bigger rocks as he started to grow up. He swallowed a few, but they went through his "system." He swallowed a bigger one that stuck and the vet had to open him up to remove it. Poor Jack got "tutored" at the same time. Odd thing is that after being "tutored" Jack never played with rocks again.