According to law you dont have any privacy as long you are using company’s computer. So to make it short , your boss has very right to kick your ass if he caught you on youtube or facebook. So how to avoid this situation from happen to you.

Its quite easy actually , you can run run an encrypted Web browser directly off a USB flash drive.The one that i know which is very secure is ironmonkey. It is very secure USB drive preloaded with a version of Firefox that automatically routes your traffic through other servers. You can purchase  1 GB version for  USD 79 , quite expensive  right. thats life you have to pay to shit , so definitely you have to pay for privacy :).