question about the rules?

I just had a quick question about the rules. Last night i was playing in a tournament of NL holdem of about 20 people.At the final table i saw a play happen that i thought was very crappy. It was down to the river and there was two people left in the hand , One guy goes all in and the guy didnt call him for a second but pulled a childish move He turned over his cards and said well since you called i will show you my cards. the guy who went all in misunderstood what he said and said okay and turned all his cards over thinking he called him. the guy then folded bc he saw he was beat. Very sly move and i didnt approve at all but didnt say much. But my question is can this guy turn over his cards and almost pretend he called to lure the other in to show or get a read. Please give me feed back. ive seen this on tv but to think what havent we seen on tv.

thanks
Jpehl