Graves jumped into the Potomac River in Washington, D.C., suit and all, as part of a fundraising effort that's going viral for 5-month-old Landon Shaw.
Landon is fighting cancer.
The Plunge for Landon started on Facebook with people posting video of themselves jumping into a chilly body of water.
Then, they challenge others to do the same and donate.
Graves made good on his challenge and in turn has challenged others including Speaker of the House John Boehner and state lawmakers Brad Lager and Mike Thompson.
To see Graves take the plunge, click here.