I am confused...
Your buddy doesn't want to let you see what is in there? Like he has top secret program or something, and they are in his PATH?
If he is trying to access this directories via the GUI (which is the sound of things since you can't use ls to view it? ) and the directory has a lock on it, then he can't access the directory with his user.
So, like GT said, and you said, chmod it, but the directory rather than the file inside it. You have to gain access to each thing in sequence. If you own something inside someone elses directory, you still can't access it without permission to enter the directory.
chmod a+r /usr/bin
would be the minimum needed for that.