Don't touch anything, green, blue, looks like it's going to be or has been used at the table in theatre. Be very aware of sterile fields, scrub staff will not like you if you foul(contaminate and therefore de-sterilise it) particularly in orthopaedics. You might see some gross or disturbing things occasionally. I would say that personally I have seen more gross things in the last 12 months than the rest of the clin eng department put together, however that is not the norm (goes with the territory when you spend most/all of the working day wearing scrubs).
