You ought not to unwrap your yuletide present before the big day. In the spirit of the season, Tyler Perry is delivering “Tyler Perry’s A Madea Christmas” to theaters without offering critics a peek. Because, you know, there are sure to be all sorts of unexpected surprises involved. Perhaps this outing won’t oscillate wildly between hand-wringing drama and slapstick. Maybe Perry’s linebacker-sized drag alter ego won’t toss off homespun homilies and PG-13-worthy sexual quips. Possibly Madea’s weed-smoking, gun-toting ways are behind her. Conceivably there won’t be a parade of “uproarious” outtakes in the end credits. Or the film might stick to the formula that has made the writer/director/star one of America’s richest entertainers. After all, Perry’s last venture into uncharted territory, his action star vehicle “Alex Cross,” resoundingly tanked. We’ll post a review soon.