before you think na tanga 'yung ON key, naisip ko yan kasi ang opposite ay OFF key diba?

i'd say sing ON key, or sing IN tune.

bianong: parang sa mean girls -- "if you can be overwhelmed, and you can also be underwhelmed, can you be just WHELMED?"

bianong: but yah, i agree with erfra.

I think it's "of" key.