Nerd Surfing is when someone (not necessarily a nerd) is surfing the internet, opening numerous, (generally informative) web pages. This includes sites such as Wikipedia. The essence behind nerd surfing is when the person sees a link(s) on one page, he/she opens the link 'in a new tab' or 'in a new window' and repeatedly does so until a chain of informative web pages are open all at once. This can often lead to a bizarre number of tabs being open, and can often create somewhat of a snowball effect.
Nerd Surfing is NOT when someone imitates surfing over a pile of upset nerds.
A - "What's that guy doing?"
B - "Oh, he's just nerd surfing the ScienceDaily.com"
A - "Dude...he has SO many tabs open!"
B - "I know right! That's some proper nerd surfing!"