One of the most inefficient methods of contraception still used today. Involves having sex at the time of month at which the woman is least receptive (physically) to pregnancy.
Since he was too lazy to put on a condom, he decided to just use the rhythm method
A form of natural family planning involving abstaining from sex for a number of days each month, long promoted as the only acceptable form of contraception by the Catholic Church. Common side effects include pregnancy.
Withdrawal is actually a more effective form of birth control than the so-called "rhythm method".