Honor Thy Bro.

Before we get started I want to make it very clear that my "Bro Code" is not the same as the usual "Bro Code" which mostly just consists of slurring the phrase "Bros before hoes bro" and then falling into a pile of their own putrid vomit. I do not advocate the phrase "bros before hoes" unless the hoe really is a hoe. The way I see it is that your friends should be willing to talk to you about why they think your girl friend is a shitty person if that's the way they feel rather than just repeating the same, lame phrase over and over again.
With that being said, we can move on to my first rule of the bro code. This is a very important rule, so pay attention. HONOR THY BRO. Basically this is just a catchy name for "don't be a dickhead". If you know that your friend's girlfriend is cheating on them it's perfectly acceptable, nay, expected of you, to let your bro know. This person is one of your best friends, they are your BRO, which is short for brother, and as far as I'm concerned family is #1.
There is no excuse for anyone to ever cheat on their significant other, and I've already covered that in a blog, so I wont go into to much detail on that subject. Basically, if you feel the need to cheat on someone you might as well just break up with them rather than keeping them around. You obviously don't care enough about the person to be faithful, so it shouldn't take much to get rid of them.
I realize that it's not always as cut and dry as just telling your friend that his girlfriend is a dirty little slut, because they're often times more likely to believe their supplier of vagina than their friends, but if you know for a fact, and can provide irrefutable proof then you have no reason not to be HONEST with your BRO. Bear in mind that she's going to lie her ass off to keep from looking like a scuzzy little gutter slut, but in the end she's more likely to come clean than to try and hide it once she's been called out. There are two reasons for this. #1 is that whores are people too... I know it's hard to believe, but it's true. Whores have emotions and a conscience, and that means that eventually they will cave in and admit to what they did wrong. Possibility #2 is that they have no soul, and for that reason they don't care if they hurt your feelings, and so they'll be willing to openly admit that they engaged in inappropriate behavior. Now, if a person were to be in perfect balance between being totally soulless, and being a decent human being, they may be able to hide their infidelity for the rest of their lives, but most likely it's going to come out at some time or another. If your bro hears the accusations from multiple bros, with multiple facts to back it up, then he's going to have a tough time just letting it go.
Will this effect your friendship with your bro? Yes, but it should be in a positive way, because your bro should now realize that he can trust you more than ever. If your bro would rather stay with someone that doesn't have the common decency to be honest with them, then they probably wont make a good partner in crime anyways, and you don't need that bro in your life. Besides, a good bro will always come around once he sees the light, and you'll be back to being bros again, you are bros after all.
On the flip side, if your bro tells you that your lady is getting around, it's your job to take it seriously. Chances are your bros don't hate your girlfriend enough to make up blatant lies. Look into it and see what you come up with. Often times you'll be presented with the name of the person that she's cheating on you with, and then it becomes as simple as confronting that person in a civilized manor and asking him if he screwed around with your lady. Generally the guy that she cheated on you with is going to be a total tool (he knew about you and still committed the crime) and will probably have no issue telling you exactly what happened. If he denies it then you can question her about it and see where that goes. You may have to play the waiting game before you find out for sure if your girlfriend is a cheap hooker, but eventually you'll break her down.
Ladies! If you get caught sleeping around, don't waste your time on the guy you were cheating on. You obviously don't care about his feelings, and you're obviously sexy enough to find another guy, so why are you wasting your time with that guy? Some guys love sluts... find them... find a lot of them... get HIV and eventually AIDs and then spread it around to all of them, so that they all die off. Survival of the fittest, or in this case... the least slutty.
I realize that I've said some harsh things above, but what it all comes down to is this: Some people aren't built for committed relationships, and those people have no business in the dating world.
Failure to adhere to bro code may result in banishment from the brotherhood of bros, bro.