In an appearance that harkened back to simpler, uglier times, Mark-Paul Gosselaar appeared in character as Zach Morris on last night’s episode of “Late Night with Jimmy Fallon.”  It had everything you were happy to forget about the ’90s: French-rolled acid wash jeans, a gigantic cell phone, and Elizabeth Berkeley before she got naked in Showgirls.  But the highlight is definitely Gosselaar playing Zach Attack’s “Friends Forever” with the Roots (starting with 1:45 remaining).  Eventually, I may one day have my mind NOT blown by the fact that the Roots are Jimmy Fallon’s house band.  I’m thinking probably the year 2028.