Nancy Friedman reports that there are currently eighty-five live trademarks registered with the US Patent and Trademark Office incorporating “OMG,” of which the earliest might be OMG Object Management Group, which dates to 1991, well before you sent your first SMS text.
Then there’s “omg!” Yahoo! uses this version, lower case plus exclamation point, for its celebrity subsite. And if there’s anything that needs lower case, it’s celebrity news. Despite this, all the feature links appear in VERY LARGE CAPS.