noun.
the act of
bopping haphazardly around the internet by hitting the "stumble" button on an installed "
StumbleUpon.com"
toolbar added to your browser--the button will take you to a random site of interest to you (based on preferences you set up before) that you are lead to "stumble upon" because others with similar interests liked it. "Stumbling" the internet is fast becoming an activity as understandable to computer regulars as what simple googling is known to be.