I went to Chicago with my friend (he needed to get his passport renewed, and didn't want to go alone). He bought my $50 train ticket, a gift for me worth about $20, and he bought us lunch at a really nice restaurant -- which cost $100+. He won't take any money from me. He said my friendship is enough. I beg to differ, and I want to get him something / do something for him since he has been so ridiculously generous and sweet, but I don't know what to do. Ideas?