How can I secure my phone when plugged into a PC?

[Android Question]

When I plug my phone into my computer, there is no security such as password protection.
Say if I accidentally drop my phone on the street, anyone can get their grubby hands on it and go through my personal items such as photos and music. How can I change it so when I plug my android into my computer, there will be a password prompt to enable computer sharing?

 

[Rukbat]

Even if you did that, there are ways to get into the memory without using the USB port.

Don't put anything on the phone that's not securely protected (say well-encrypted, or something having meaning only to you).