It's a joke. Doofy conservatives picked up the habit of saying "Thanks, Obama!" with his every perceived misstep, to the point where it became a cliche. Though by the end of his presidency, many people where saying thanks to him quite sincerely---something that few seem likely to do with the current administration.
There is a liberal I know who always posted "Thanks, Obama" on Facebook when something good happened (like oil prices going down)