The Best Day of Your Life (1970)

Derrick's best friend is now married. Upset by the change-after making so much progress together as friends and business partners-he never thought he'd settle down. Unlike his friend, Derrick dreads the idea of marriage and decides he'll never tie the knot. Until one fateful and frightful day, Derrick falls asleep and the unexpected rears its head. Worse yet, it's more real than he thinks.