Goddamned Bats/Simulation Game

• Anything with an Ion Disruptor in X3: Reunion. This weapon is extremely effective against shields, automatically locks on to anything in a wide fire arc, and has no travel time. While it can't damage your ship's hull, it is extremely effective against shields and can destroy equipment once your shields are down, as well as making you easy prey for lasers, missiles or collisions. Since all ships are susceptible to friendly fire, even friendlies using the Ion Disruptor turn into Goddamned Bats. As if it wasn't already annoying enough, using the weapon yourself when there are non-player-owned friendlies around turns you into a bat, and they'll instantly attack you.
  • Kha'ak fighters in X3: Terran Conflict qualify for capital ship captains. Individually they're no threat at all since a few good flak hits will splatter them, and their weapons are really weak. Clouds of them can wear you down. Oh, and they spawn continuously as long as you're in a Kha'ak sector.
  • M5 scoutships in general, but particularly the Teladi Harrier, Yaki Fujin, and Xenon N (the only common M5's with credible weaponry). They come in swarms (often alongside ships that actually pose a threat), and are too fast to hit with most weapons. Get enough in clear space and you basically need a capital ship's flak guns to clear them all out.
• Spore's space pirates.
• Here's one from an old-but-good flight sim, Total Air War: any form of antiaircraft gun. Particularly the ZSU-23-4s and Vulcans. Normally they're not a threat if you fly high or if you're packing guided missiles, but when some bright spark in mission control decides that the best way to use your F-22 is to load it with unguided bombs, rockets, and cannon shells, all of which require that you fly low to attack with any kind of accuracy, those AAA vehicles with their mixture of More Dakka and Improbable Aiming Skills can and will turn your aircraft into shrapnel. And worst of all? They're everywhere!
• In the Ace Combat games, normal mook planes and SAMs become annoying when you need to kill aces while they're around. They may ascend to Demonic Spiders level in Ace mode, where a single missile hit will almost always destroy your plane. The ballistic missiles in Ace Combat 04 are just really annoying to shoot down. If you watch the flight path replay at the debriefing, you'll notice they goes side to side and up and down in a sawtooth pattern. Even the Game Breaker QAAM missiles have a hard time with this one.
  • The drones is 6. They are more maneuverable than the enemy aces.
• The Naval Ops series has PT boats, tiny little things that are no real threat to a larger vessel and which usually go down with one good shot from your main guns. Then you meet the advanced versions in your second playthrough, who carry lasers and shields and cannot be locked onto. Both types are fast enough to be tricky to hit.
• In Animal Crossing catching certain very common fish and bugs is this. Sea Bass in particular are a well known annoyance, as on most days other than rainy days you'll probably catch them much more than the fish that are actually worth anything. Mosquito's are a more straight forward example of this trope though. They are attracted to you instead of running away like most other insects, so if you're fishing and it bites you the player reels in their line causing the fish to disappear.