All too common onguard. Another thing to keep in mind is this : Imagine playing 2/5, and you're in one of the blinds with a 5$ chip posted. Someone raises to $20, and gets a couple callers. You want to make it $105. Tossing out a $100 chip is still just a call by the single oversized chip rule. You need to grab your blind chip along with the black chip and toss them out together to make it a raise, or verbalize it ldo