Employee incentives can take many forms, but Brussels ad agency Mortierbrigade has come up with a novel way to motivate its visiting creative interns. Specifically, it upgrades their accommodations when they achieve good results, while poor efforts can land them in “the basement.” When international interns arrive, they start off on the ground floor of the Mortierbrigade Hotel, which is essentially a house next door to the company's Brussels offices that has been converted into housing for visitors. Accommodations on that ground floor — known as the “Tent for Two” — are designed to resemble a sparse camping area complete…