Oh my days Definition 1 of 3Pro Tip 1/3Emotional Punch Boosts the emotional impact when you react to something surprising. Oh my days, she won the lottery! Pro Tip 2/3Casual Conversations Best used with friends or in informal settings, not in formal situations. Oh my days, this is the best burger I've ever had! Pro Tip 3/3Not Literally Days Doesn't refer to specific days; it's just an expression of astonishment. Oh my days, how did you do that trick?