this 4koma was posted before in 4chan's /a/, and was translated by Anonymous:
[Since Summer Break's almost over...] [Everyone came to the beach to play.] "Huh? Where'd Sachiko go?" "Eh? Now that you mention it..." "She went somewhere with some guy just a while ago." *pantpantgruntgruntetc* "........ what are you doing?" "Eh? Isn't the beach where you go to have car sex?"
Since Summer Break's almost over...nhaa!Ahh...good! More!Eh? Isn't the beach where you go to have car sex?*squishi*Everyone came to the beach to play.Huh? Where'd Sachiko go?Eh? Now that you mention it...She went somewhere with some guy just a while ago.*Squishi*Ahn........... what are you doing?What are you doing?