Don’t fart in an Apple Store.
It has no Windows.
No Farting in Apple Store
Explanation
Explain Bear
Listen up, chucklehead! The joke is that "Windows" is a popular operating system, but it also means openings in a building. Apple Stores don't have "Windows" (operating system), and well, usually buildings have windows to let air circulate which will help in fart situation. Get it now, dummy?