Borrowing a pen
If you want to make friends, try borrowing a pen from them and returning it to them later with a smile on your face. This may be a smooth way to actually get into a conversation with someone that could potentially lead to a friendship. Who knows how far a pen could take you in life?
If the person you ask who clearly has many pens, does not want to lend you any, that is a clear sign that they are probably not interested in an interaction with you. So the simple request of borrowing a pen can actually help you determine who is friendly and who is not.