Friends an money help?

Ok so I'm planning a clubbing vacation in Cyprus, my friend Stuart is going and Stuarts friend I don't know is goin , they are currently both 60 miles from me ATM an they claim to of booked it, I trust my friend but I don't know the other guy he seems cool . But staurt says he's paid for me an wants the money tomoz ( which I'm fine with as long as it's been booked) I worried I may be being hung out to dry. But I have no proof I think I'm being irrational , but am I ? Should I trust them. I must add it's been done online so a majority needs to be paid upfront .