A few thousand people will be happily placing their sanity in question by jumping into the frigid Chesapeake Bay. But, hey, at least it’s for a good cause, raising money for Special Olympics Maryland. The big plunges are set for 1 p.m. and 3 p.m. Saturday, with a pee-wee and family plunge set for 11 a.m. Other plunges, for school and corporate groups and police, go off Thursday and Friday. There’ll also be live music (performed inside the heated Rams Head Ice Lodge) Friday and Saturday, from groups including Loose Ties, Hot Tub Limo, Foreplay, Here’s to the Night and Vinyl Rhino. Sandy Point State Park, off U.S. 50 just west of the Bay Bridge. $75 in pledges to join in the fun. somd.org.