A cornball is basically, the new geek. Just like a nerd used to be a lame but a geek was just completely off the scale lame. Now a geek or computer geek is someone who highly educated, usually through personal experience rather than actual institution education, in common computer softeware and the internet in general. He or she more often than not will also repair PCs. Pirately tendencies also usually apply.
This definition does not encompass cornballs in total. There are many varieties and sometimes a cornball IS a lame. Examples are shown below.
Police (Definitely - all the wrong things)
The 40 Year old Virgin
Charlie - Me, Myself and Irene