She always steals your thunder.
aka Anne Hathaway's character Kym in Rachel Getting Married
Kym—fresh out of rehab with chip firmly affixed to her shoulder—is the epitome of the thunder-stealing friend. Ok, she's technically Rachel the bride-to-be's sister, but close enough. You announce you're pregnant hoping to dissolve a fight. Without uttering so much as a "congrats," she announces it's unfair to change topics like that. Whether its with family or out flirting at a bar, some people always need to be the center of attention. Lucky for you, they don't always have to warrant yours.