Silly Johnny Sasaki through his idiocy attracts the attention of MGS 4's first boss, the FROGS aka the Haven Troopers, but this only just registers as a boss battle because a) the FROGS aren't that tough and b) you've got both Meryl and Rat Patrol Team 01 helping you out. This game is so ridiculously generous with rations that there's a good chance you'll be extremely well stocked up by the time this fight starts, so unless you're an MGS newbie, there's absolutely nothing to worry about. It's a solid enough way to get used to the game's action mechanics early on, but at the same time, it's not really at all remarkable or memorable. It's not like the FROGS strike fear into the player's hearts every time they show up like, say, the Skulls.