Nope, although this holiday is not exactly a wide-spread phenomenon.
Our buddies over in the New World should be a tad more familiar with it, but still...
Winter-een-mas is a holiday invented in a cartoon (Ctrl+Alt+Del) by one of it's characters.
It has since been celebrated by followers of the cartoon and getting somewhat more widespread a few years after.
It seems to have calmed down the last few years though.
But hey, if I can wish someone a happy day, why not go for it?
Just for the record, winter-een-mas is always the last seven days of January, not one particular day.