If you're stuck at home and miss the good old days of idly channel surfing, Sling has something for you. The internet-based cable TV alternative announced Tuesday that it's making part of its service free for new customers at night while everyone is sequestered indoors. From 5 p.m. ET until midnight every night, anyone who signs up on Sling's "Happy Hour Across America" website can watch TV to their heart's content. There is, of course, one major caveat to this.