Tonight’s Best Bets will be all Christmas, all the time – or, at least, all devoted to Christmas specials and special presentations on this evening’s TV schedules. Start, at 7 p.m. ET on TNT, with the now-annual tradition of a 24-hour nonstop marathon showing of 1983’s A Christmas Story, about little Ralphie’s quest for a Red Ryder B.B. gun. This marathon also runs, beginning at 8 p.m. ET, on sister network TBS, so for a solid day, tonight and tomorrow, you can watc