Clown Corps: McBell's stealth attempts often run into the problem that she keeps Breaking the Fourth Wall to narrate her actions, and this is, as repeatedly made clear, totally audible to the people around her.
In Darths & Droids episode 2173, Jim surprises the GM by describing his usually bizarrely brainless character avoiding detection by another by actually using pretty good sneaking strategy. Then, having sneaked, he calls out loudly to the enemy he was hiding from.
Lampshaded in thisDominic Deegan strip. Not to mention Spark's "Death from above!" This gets repeatedly played with.
Actually encouraged by the rules of combat in Drowtales, where one's honor dictates that a one-on-one battle should be opened with a formal challenge shouted at their opponent. Even so, Syphile's use of this and Quain'tana's expression firmly put her into Too Dumb to Live territory, since Syphile had a clear shot and might well have succeeded had she not done this.
Everyday Heroes: Jane's backstory includes a couple scenes of Wrecking Paul noisily smashing something offstage with his ball-and-chain weapon while the Jane Gang is trying to be stealthy. It is later revealed that Paul is a serial killer who is using the missions as an excuse to bludgeon women to death.
Fans!; a character makes a suicide attack against a totalitarian dictator while yelling "sic semper tyrannis", which gives her enough warning to raise her shields and survive.
Also apparently Sam's race are such heavy sleepers that singing during a burglary is traditional on his home planet.
Subverted by Sawtooth in this strip. Despite being a ten-ton terraforming robot and smashing through walls to get at his goal, he gets away cleanly because the power is out.
Sawtooth: No alarms. Like the wind. I'm a subtle typhoon of stealthiness. Probably helps that the power is still out.
While it's unclear just how much noise they were really making Zeetha compares Oggie and Maxim trying to sneak up behind her to elephants, much to Oggie's offense. Hey! Dese is prime goot sneekin-op moves!"
Gilgamesh Wulfenbach manages to blow his surprise attack on a guy with a machine gun assault robot by shouting at him. Turns out that the guy also has a pistol.
El Goonish Shive subverts this by making the angry sneak attack a distraction.
Invincea from Invincea and the Warriors from Hell has been cursed, and some may say blessed, with absolute silence. The same cannot be said for most of her friends.
When Elan makes a low roll on his Move Silently check, he decides to let the rest of the party know by shouting "I GOT A 4!" He does it again in #766, except this time he GOT A NINE! (he's wearing magic boots that give him a +5 bonus to Move Silently checks).
In Recursion, Jade finally manages to get her stolen gauntlet-phaser to boot up while she's hiding from from some security drones. It boots up all right; right into a cheery holographic welcome message and an offer to register the unit with the manufacturer. Then it shuts back off to download a firmware update, so not only does she still not have a working weapon, but everyone in the base now knows where she is.
Turns up in Skin Deep. Myra is not ready for stealth and subtlety until she has her chainsaw at hand.
Skin Horse: When Valiant and Alfa Alfa manage to coax Echo Bravo into joining in the latter's Mook–Face Turn, Echo Bravo loudly declares them a TOP SECRET REBEL FORCE! ...from their tent, surrounded by other tents full of Anasigma Mooks, all of whom can hear him.
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