How can you prevent crabs?

Agree w Abstinance. Crabs (pubic lice) is usually transmitted through direct contact during sexual activity. Crabs (phthirus pubis) can also be spread by vector transmission. Wearing someone else’s clothes that are contaminated or infected towels, bed sheets or towels can give you lice.
Abstinence. This has never been popular. Take a close look at a potential partner, especially for little eggs on the pubic hair. Should you encounter these familiar little creatures, both you and that special person or persons should cover yourselves up from head to toe with an appropriate crab-killing shampoo for the appropriate length of time. A little bit comical, but no long-term danger. Good luck.