In the movie MacGruber, Will Forte wears Ray-Ban 3025 Aviator sunglasses.
Will Forte actually sports several Aviator type sunglasses, but it's not 100% sure that they are all Ray-Bans. Some of the frames are silver and at least one pair has the gold (arista) color.
What can be noticed is the special leather side protectors that MacGruber sports on his sunglasses. One black (or brown) and one white version can be seen in the trailer. These side shields would have to be bought separately for the Ray-Ban Aviators. A brand that has these shields is Julbo, in their Vermont and Micropore range (see here).
The Ray-Ban RB3025 Aviator is available in several sizes and color combinations.
Get the classic Ray-Ban RB3025 Aviator online at the official Ray-Ban website, on Amazon.com, Amazon.co.uk or take a look on eBay.
Also available with Polarized lenses (as seen in the film) at Ray-Ban and Amazon.
In a promotion that runs until May 31st, you can win polarized Ray-Ban Aviators on the MacGruber film website.
Reference: Ray-Ban RB 3025 Aviator