We have all been lied to since season 1. This is from an HBO featurette on the costumes, and the original gif is actually Nikolaj Coster-Waldau saying the tail end of "fantastic."

Start around 06:00 mark: 

Black and White:

Reddit comments:

http://reddit.com/r/HighQualityGifs/comments/2bxzpf/got_jaime_lannister_saying_nice_remake/

http://reddit.com/r/gameofthrones/comments/2by2sc/no_spoilers_s1_jaime_lannister_saying_nice_gif/

More NICE gifs:

http://pandawhale.com/post/30203/jaime-lannister-nice-gif

http://pandawhale.com/post/43815/nice-picard-nicely-done-gif

http://pandawhale.com/post/51836/christian-bale-nice-gif

http://pandawhale.com/post/20339/louis-ck-thats-very-nice-gif

http://pandawhale.com/post/19259/so-i-got-that-going-for-me-which-is-nice-bill-murray-gif

http://pandawhale.com/post/36461/community-britta-shirley-oh-thats-nice-gif

http://pandawhale.com/post/48776/key-and-peele-nooice-gif-noice-nice-nice

http://pandawhale.com/post/41219/south-park-nice-gif