If you want to avoid an unplanned pregnancy or getting an STI/STD, your best bet is to use a condom! Being concerned about what others think keeps many of us from talking openly about what we want when it comes to sex and protection. Talking openly and honestly about condoms, and planning ahead about how to protect yourselves from an unplanned pregnancy and/or catching something is so important!
Ideally, you should bring about the topic of using protection, such as a condom, before things even get close to the bedroom. Just talk openly and honestly about your expectations with your partner, that way you will both be prepared to use protection.