Well, perhaps "advanced" isn't the correct term. It's certainly risky indeed, to take an unrestrained rat places. And a huge responsibility that I think many do not think all the way through.It's called Shoulder Ratting. It is extremely dangerous, requires a well trained rat/human pair, and you still risk losing your rat every time to take them out. Rat Daddy has great info on it, how to tell a good shoulder rat, how to test them, the risk involved, not to mention amazing stories about his Fuzzy Rat. It's a very advanced type of rat ownership, as he discribes in his info thread. It's not for new owners or those who are faint of heart.