How do I enable a dynamic IP?

I wanted my ip address to change every time I hit refresh. Is it possible?

 

Assuming you are refering to the IP that identifies you on the internet (as opposed to the IP on your LAN), this IP is assigned to you by your ISP and therefore there is nothing you can do to change it from your computer (aside from swithing ISPs).
And to echo TxTazDad, I see no (legal) reason to do so.
If you are refering to your LAN IP, that is assigned through DHCP (if connected to a server) or through Zeroconf (if no server is used).
Unless you are trying to confuse your home or office network, I see no reason for wanting to change that either.