Kissing Booth Achievement
Kiss a poster in a locker
This is a Metal Gear Solid 2 achievement.
When you find a locker with a poster on it, get into it, then press the First Person View button. You'll hear a kissing sound. There are a lot of lockers with posters on it in the game. A quick place to look for is in Deck A crew's quarter, Tanker Chapter.
Refer to this video for further assistance: