1. Thou shalt never flirt with thy bro's sister, unless given express permission and a written waiver, signed in blood and notarized by a squad of lawyers.

2. Thou shalt always celebrate thy bro's victories, no matter how small, with high fives, fist bumps, or a round of drinks, unless thou art lactose intolerant, in which case, lactose-free beverages are also acceptable.

3. Thou shalt never reveal thy bro's deepest, darkest secrets, even under threat of torture or blackmail, unless thou art willing to face the full force of his revenge—unleashing a horde of spiders in thy bed or signing thee up for a subscription to "Cat Fancy" magazine.

4. Thou shalt always offer thy bro constructive criticism, but never tear him down with harsh words or insults, unless thou art prepared to face the wrath of his "I'm fine" response.

5. Thou shalt always cover thy bro's tab when he forgets his wallet, unless thou art a broke college student surviving on ramen noodles and dreams of winning the lottery.

6. Thou shalt never let thy bro drunk text his ex, post questionable selfies on social media, or engage in any other regrettable behavior while under the influence, unless thou art willing to serve as his designated sober babysitter and guardian of his dignity.

7. Thou shalt always offer thy bro a shoulder to cry on in times of heartbreak, breakup, or the cancellation of his favorite TV show, unless thou art too busy binge-watching said show to care.

8. Thou shalt always lend thy bro a sympathetic ear when he rants about his boss, his ex-girlfriend, or the inexplicable ending of his favorite TV show, unless thou art secretly enjoying the drama and plotting to turn it into a bestselling novel.

9. Thou shalt never let thy bro go into battle without proper backup, whether it be a video game raid, a paintball skirmish, or a heated debate about the best pizza toppings.

10. Thou shalt always respect thy bro's personal space, whether it be his man cave, his designated spot on the couch, or his secret stash of snacks hidden in the pantry, unless thou art prepared to face the consequences—namely, a swift kick to the shins.