Where I grew up they're one of the first things you learn about because they sting like buggery DX (and the second thing is probably not to try to pull unripe mangoes off certain trees because if the sap gets in your eye well that stings like buggery too)
I remember seeing some gigantic ones at some place we visited on holiday, my mum couldn't stay in the same room after glancing at them as they creeped her out too much XD
You've managed to avoid the sting so far?
Unfortunately, no. I've been stung by a small one, maybe 2-3 inches (8 cm) long, on my left calf when I was in the third grade. It felt like a bee or a wasp sting. Thankfully, the American-trained nurse in our school knew what to do. I did not tell mum about it or she would have chewed my head off. XD