When the crowd responded to the show so positively, we realized we were 'onto something'. [=we had done/discovered something important, special, etc.]
Scientists believe they are 'onto' something big. [=scientists believe they are close to making an important discovery]
Don't try to shift the blame 'onto' me. [=don't try to blame me instead of the person who should be blamed]
(..) and I got the TV like this. A big old thing. I couldn't see shit. Then I hear this voice. "Freeze, kid, hands in the air." I was standing there, holding onto that TV. Finally the voice says: "You hear what I said, boy?" I say, "Yes, sir. I did. But if I drop this, you get me (..)1994 The Shawshank Redemption