Never played it either. Looks like it asked random trivia questions that I guess kids wouldn't know.
http://allowe.com/games/larry/tips-manuals/lsl1-age-quiz.html
"Peter piper picked pickled peppers" seems weird to me as an age verification, but maybe that's because the game is old?
Was this actually an age gate, or was it a form of copy protection where the answers are in the printed manual?