I know you are, but what am I?

No details should be necessary. Most of us have heard this taunt in an argument, and know what it means. In case it’s new to you, here’s a solid reference to help you understand its meaning.

So, it’s me asking. I will not flag ugly responses and ask (beg) the moderators to allow whatever personal attacks my fellow Jellies wish to post. I will not respond to criticism or to praise. I just want straight answers, or trolling if that’s all ya got. I know you are, but what am I?