나는 더운 날에 해변에서 흥분하기 시작했다.

On a hot day with my boyfriend at the beach, I started to get excited watching him all wet diving into the sea. So I started touching myself surreptitiously so that the people who were on the beach wouldn't notice that I was really wanting to masturbate there during the day, even lying on the sand under the sun while I was tanning.