One of the most underrated movies are our time. You walked in thinking it was a joke and came out realizing it was awesome. (Not to be confused with "Bring It On Again," which was a travesty and brought shame to the cheerleading community.)
You didn't go to Woodstock. Your parents didn't go to Woodstock. Your grandparents didn't go to Woodstock. (But they probably lied that they did.) Three generations of your family didn't go to Woodstock but all three generations love the poster, so at least that's something.