He told his shocked campmates that as long as he wasn't voted out on today's (November 27) show, he would be in the money.
Speaking to the group, Bristow said: "There's a lot of money on today. I told all the boys to whack the bookies that I'll get halfway, so if I go out today, I'll lose the lot. It's worth £20,000 today. £20,000 to win £50,000."
Noting Charlie Brooks's shocked reaction, he said the bet was placed by "three of us, don't worry".
Rosemary Shrager said later: "Oh my God, he's actually put a bet on. He's put a very large bet on.
"If he gets through to the last six, he's on a £50,000 winner. Can you believe it?"
Bristow looks to have won his bet, as Rosemary Shrager was eliminated earlier this evening (November 27), seeing him through to the final six.
I'm a Celebrity...Get Me Out of Here! continues tomorrow (November 28) at 8.30pm on ITV1.