A link cascade is when one is surfing the web and reads something/looks at something then, noticing a link, clicks it, reads/looks at it, notices another link, clicks it...
And the cycle continues.
*Sign into MSN*
*MSN today pops up*:
"Britney Spears admits to killing Micheal Jackson!"
*Clicks link & reads*
*Sees another link*:
"Paris Hilton to become president?"
*Clicks link & reads*
*Sees another link*:
"Celebs at their worst! Horrible pictures of all your favourite stars!"
*Clicks link*
2 hours later...
"Shit, it's already time for bed? That was a really bad link cascade!"