Question

why do we get tears when we yawn

Answer 1

Part of the reason is that when you yawn, you squeeze your eyes tightly shut. The way that tears flow is that they come out of your lacrimal gland, which is on the upper outer side of the top of your eye; they then flow - in a film - across your eye obliquely downwards and inward

Answer 2

no, we don't get tears while yawning