Lady Gaga surprised fans by joining an icy lake plunge to help raise funds for the Special Olympics.

The Poker Face singer was seen on the shore of Chicago’s Lake Michigan with her actor fiance Taylor Kinney wrapped in towels after the dip.

ctor Taylor Kinney and his fiance pop star Lady Gaga
(Barry Brecheisen/Invision/PA)

The newly-engaged couple were seen messing about with Chicago Fire actor Taylor removing his shirt despite the temperatures.

Actor Vince Vaughn
(Barry Brecheisen/Invision/PA)

Actor Vince Vaughn also made the plunge, but unlike Taylor he kept his shirt on. Vince, who is from the Chicago suburb Lake Forest was dressed in a Chicago Blackhawks jersey and jeans. The actor went in up to his knees, then eased himself down backward in the water.

Actor Vince Vaughn
(Barry Brecheisen/Invision/PA)

Some 4,500 people completed the dip into the icy waters and Lady Gaga’s appearance wasn’t just a treat for fan. Special Olympics Chicago President Casey Hogan said the singer’s appearance was “a very nice surprise.”

ctor Taylor Kinney and his fiancée pop star Lady Gaga
(Barry Brecheisen/Invision/PA)

Last year comedian Jimmy Fallon jumped in wearing a suit and tie, and helped raise more than US$1 million (£648,000).