When I was still at school (but already with several years training as an Olympic weightlifter) I guy at school asked me how much I could bench. I only benched once or twice a week as my training was focussed on Olympic lifts, and I told him I get up to around 10 reps at 160 lbs. A few days later he told me he could do over 200 lbs for reps of 10. I called bullshit, and he challenged me to a contest.
So off I go to his gym (more of a bodybuilders gym than a weightliftng gym). Then off he goes to a bench MACHINE, set up with a leveraged type bar, and put the pin into the machine at 200 lbs. After struggeling to do 10 reps he got up, and proudly looked at me "See, I told you?". You do it now. "That's not a benchpress" I told him and I got on and did 20 easy reps. "Lets go do a REAL benchpress" I said.
So, off we go to a proper free-weight bench. I did a warm up set at around 100 lbs, and then he gave it a go, an barely made a single rep. I then put on 160, and did as many reps as I could ( I think I did 20 reps or so, trying to make it look as easy as I could). He tried, and WOMPH, down went the weight on his chest. "Do you need help, I asked, lightly keeping the pressure up on the bar so he would not get hurt". "yeeeeeah", came the reply, and which point I lifted up the weight. He left, with his tail between his legs.
Even funnier, was that he had invited a few mates to watch how "he was going to beat that weightlifter in a contest".