In reply to chrisw88: When you knock something over or drop something you shout "below" very loudly...did this at the office once when I knocked my tea off the desk with my elbow!
When there are more marks from old scapes and scratches on your forearms and backs of your hands than there is undamaged skin.
When you convince yourself that a badly placed micro-nut in brittle friable rock will be a perfectly acceptable way of stopping a 30 foot fall.
When you hold the bottom of ladder for someone and tell them to "climb on" when they ask if you're ready.
When your forearms are bigger than your biceps.
When you have old, written off bits of gear tied on to the pullcords of lights just to make you feel more at home.
When, while having a conversation with friend/housemate/colleague, you hang from the doorframe instead of standing in the doorway like other people would do.
When you get free drinks in pubs for traversing the building...climbers pub.
or...
When you get thrown out of pubs for traversing the building...non-climbers pub.