Here is a social courage challenge especially for Westerners (tweens through adults), for whom physical affection between friends tends to be somewhat reserved. Next time you are in public with your closest friend, link arms, hold hands, or walk with arms across one another's shoulders. Do you feel self-conscious? Are there places or situations where you feel less comfortable doing this than in others? What a great opportunity for you and your friend to have a conversation about how others see you and your friendship, and how you yourselves see it. We too often forget that in many parts of the world, this is perfectly standard practice between men and men, and between women and women. And no-one assumes they're gay!
Other ways to test the limits of "personal space" and social courage is to stand close to the only other person on the elevator instead of retreating to the opposite side, or taking a seat near the only other occupant of a bus, movie theater, park bench or restaurant. You might get some dirty looks! Go ahead, test yourself. What sorts of feelings does it bring up for you?