Peggy Carter wrote the first S.H.I.E.L.D. agent manual, and it was a lot of "so one time (insert Howling Commando here) did this stupid fucking thing and it somehow worked and they didn't all die, but please, for the love of all that is good and holy, do not do the thing unless you've a matchless sniper, an adamantium shield and a squad full of idiots led by a reckless moron". Peggy got Phillips to help her write it, and Howard tried to help, so they sent him an itemized 47 page list of all the ways in which he had been a contributing factor to Things That Should Not Have Worked, and told him to come up with alternate ways he could have acted that would have limited such behavior and that kept him from accidentally almost destroying the world for three months, a personal best.
Clint is Peggy(and Fury)'s secret favorite because he keeps doing Howlie-worthy shit that either gets a place as an addendum to Howlie entries in the manual, or get their own entries. At a rate even the Howlies would have been hard pressed to keep up with.
Then Natasha happens. (Agent Manual, 65th edition, section 1: What Not To Do, page 956: Do NOT drag the Russian Assassin home and ask the Director to let you keep it.)
Natasha decides the manual is actually a check-list of things to do in the field when she's bored. Bonus points if she does it with even more improbability-of-success ridiculousness. She actually keeps score. Everyone else gives up. Coulson and Fury don't even TRY to tell her not to do things any more, and they don't let her have any copies of new editions of the Manual, because she will. And nobody tries to out-do her. Except Clint, Rogers, and Barnes. And Darcy. They love the challenge. Tony just records it all to rewatch the shenanigans later.
There are annual competitions at S.H.I.E.L.D. Academy to see who can most faithfully pull off the most bizarre Howlie war stunt with the least amount of injuries. Phil Coulson is the judge for historical accuracy. The Annual Academy Howling Commando fair is a lot like those civil war reenactor group get-togethers, and it's not officially condoned, but unless someone wins the That Is Not How Grenades Work trophy from the reigning champ, Fury ignores it, because he is damn proud of that trophy.
When you go to any sort of job training that covers the use of a fire extinguisher, you will learn that you remove the pin that prevents the handle from moving, aim at the base of the fire, and then pull the handle. Also, there will most likely be some smartass loudly declaring “pull the pin...and throw.” Unless you're at SHEILD Academy. They know better. Because Fury. On a training mission, Fury actually threw a fire extinguisher in a firefight, and taking some number of people out (accounts vary, but it was probably not more than 6... probably), because let's be honest, those fuckers are heavy.
Then later in the same fight, he put out a fire with a grenade. The concussive force extinguished the fire. Which is how Fury won the That Is Not How Grenades Work trophy. No one has been crazy enough to try it again, or attempt any other Not How You Grenade trick better than that.
It was also the first of Fury's reports that made it all the way to Peggy's desk. She head-desked repeatedly and then added it to the manual, and made sure to keep an eye on that recruit. In short, Fury's director now because he can out insane you.
Straight out of the Academy, Clint made highest marks in Most Deadly Application of Lipstick competition since Director Peggy Carter deigned to show up to "The Fair" in its third year.
The Howling Commando Legacies show up every year, regardless of whether or not they're even SHIELD agents. Sharon Carter convinced the pilot of her quinjet to fly over the Academy on the way back from an op so that she could parachute out and make it on time. She had a broken arm and seventeen stitches in her head, but was pleased to defend her three year winning streak in Best Use of an Empty Pistol at Short Range.
Natasha Romanoff submits footage every year to the Dumbest Quip in the Face of Certain Death category. No one has any idea why she knows so many obscure references to eighties and nineties cult movies when she was raised a Russian spy.
Tony Stark has been awarded the I Don't Think You Understand the Basic Principles of Physics engineering award seven different times, despite never having actually participated. Due to the Care And Keeping of Erratic Egomaniac Geniuses section of SHIELD's manual, inspired by Howard, Tony has not ever been informed, despite that being the ONE award he would show up on time and sober to receive.