It is important to understand when and where you can and should yo-yo. When you are in a room full of other people you shouldn’t be yo-yoing. There is too much risk in hitting another person and harming them. You could quite possibly also harm property or the yo-yo itself. This doesn’t go to say that you can’t yo-yo, if you are given a space or have learned a few tricks that don’t need too much room to perform by all means entertain the others and amuse yourself by yo-yoing but remember to be caution and aware of your surrounds at all times.
Additionally it is important not to yo-yo near pets, some of them may mistake a yo-yo for a toy of their own (like dogs and cats sometimes will do) and you could smack them with the yo-yo, hurting the pet considerably depending on how fast the yo-yo was moving.