We're not in the future yet, so you can't rely on your condom to provide lubrication for you (even pre-lubricated condoms could use some help). Lube helps get rid of some of the friction that happens when a penis enters a vagina or an anus , and friction is bad because it can lead to rips. That's one of the reasons why sex educators always suggest adding more lube. Also, slippery sex just tends to feel better . But it can be easy to skip that step, especially if you're not familiar with lube, or you haven't found a brand you like, or you're having spontaneous sex and don't want to pop into the drugstore. So, until, we get these fancy new condoms in our hands, try to remember to keep some lube on hand.