Back in the seventies ... Spend an hour or two - or a full four seasons - in Mr. Kotter's classroom again, joining in the antics and reminiscing about wiseguy teachers and goofball high schoolers.

Before cracking jokes as Deadpool, Ryan Reynolds had his own high school mishaps—one being his famous failure in drama class.

While this revelation might be shocking to the average viewer, "Welcome Back, Kotter" was never a shrinking violet when it came to its subject matter. Read more: Dumb Reasons These TV Shows Were ...