Bally Total Fitness monthly membership?

My friend called ballys and he told her that he would give us 2 weeks free until we had the money to pay and we should come in today and talk to him. so we went and he tried getting us to pay right there and then he told us that he'd give it to us as 50 for the first person and 25 for the next two or 100 for 3 of us and he'd also throw in a trainer. he said we can cancel whenever we want and its monthly payments of 25 but im still not so sure about everything and my mom is saying how its probably a scam. any advice?