Why “42”? Ask your not-yet-Christian friends, “What is the answer to life, the universe and everything?” Be prepared to share with them the answer you have found in Jesus Christ.
You will understand exactly what all that is referring to if you are familiar with the radio and television series, books or film of Douglas Adams’ “Hitchhiker’s Guide to the Galaxy”. If your friend also knows that “the answer to life, the universe and everything” is “42” you can use that reference to introduce questions of the meaning of life. With thought you can find all kinds of points of correspondence with the gospel in popular television programmes, books, films and songs. But even to list some of the possibilities would be self-defeating.
You need to come up with the connections yourself because that way of leading into conversations about spiritual things is only effective if it taps into an element of culture which you are familiar with and your friend shares. If that is the case then almost anything anybody has watched, read or listened to and wants to talk about can open a door to talking very naturally about Jesus. Listen sensitively and prayerfully and then take every opportunity!