Irish goodbye is a slang term with its origins in the Irish-American neighborhoods of New York City and Boston. The term refers to the practice of inconspicuously leaving a place where one has gathered with friends (usually for quite some time) without ever formally announcing that one is leaving.
Note that an Irish goodbye requires a conscious decision by the person to leave without bidding au revoir. It is a decision undertaken not for any emotional reasons, but solely as a matter of convenience. The Irish goodbye allows a person to disappear from a function with the utmost expediency without spending extra time on "thank-yous" etc.
i've tried such strategies but then people are always texting or asking the next day - hey where'd you go? you still here?