Just a small clarification, you can't carry bitcoins with you either. Bitcoins are not little pieces of information you can hold on a thumb drive, but an agree

Just a small clarification, you can't carry bitcoins with you either. Bitcoins are not little pieces of information you can hold on a thumb drive, but an agreement by the network that a certain balance belongs to some address. You are absolutely tied to a server for transactions, and there is a trusted third party required. That third party is the bitcoin network itself. It is impossible to make a bitcoin transaction while offline because making a transaction means updating the state of the network, not merely giving somebody information.