(#TCOT stands for top conservatives on Twitter--a hashtag that conservatives often include with tweets of a political nature. #WHChat was the hashtag that needed to be tweeted if one wanted to ask the White House a question.)
The White House (it's unclear if Deese sent that particular tweet) responded, with a link:
Clicking the link sent you here:
And with that, the White House rickrolled its Twitter followers.
A rickroll, of course, is when you trick someone into clicking a link to Rick Astley's 1987 song, "Never Gonna Give You Up."