<human>: NSFW because of sex and lakes. This happened over the summer, but I figured it should be shared here. I was 18 years old and had been dating this girl for around a year, so we had been having, like most teenagers, as much sex as possible. One night we were walking down the beach on Lake Michigan on the north shore of Chicago, in an area where police don't have much to do besides break up rich kid parties and give speeding tickets. Anyway, so me and this girl decide to go swimming completely naked, and we end up starting to have sex in the water. All of a sudden I turn to see flashlights coming towards us, and a voice yelling at us to get out of the water. We're crouching just heads below the waterline, as two officers are telling us to get out of the water now. One of the officers notices that their is a pile of clothes in the middle of the beach and says "We're just going to turn around and give you two a second to put on clothes, but the beaches are closed and you have to leave". Both the officers turn around as we scramble to get our clothes on soaking wet. We walk to the road together not saying a word, when my girlfriend realizes she dropped her phone in the sand while changing. She explains to the officers that she lost it, and we all go back together and they use their flashlights to find it. After all of that, they get into their squad car, give us a "be safe you two", and speed off. Don't have sex on public beaches

Provide a brief overview of the text.
<bot>: Went swimming naked and had sex, caught by police, police turn their backs while we change, girlfriend loses phone, police help find phone