What does Birthday'd mean?

Birthday'd meaning in Urban Dictionary

A prank concerning someone becoming in a buddy's Facebook account (either by understanding the code or because of the target leaving their particular account signed in) altering the birthday associated with the target to a higher or same time. The outcome becoming that target will undoubtedly be bombarded with several birthday celebration emails on every day that's not their particular birthday. Doing this many times in a single few days will yield top results.