PROMOTIONS is a meme once frequently seen on 4chan's supposedly "work-safe" boards. It started in a thread where a user complained "I GOT FIRED", implying that he had been caught looking at NSFW images at work. Later in the thread someone else posted "I GOT PROMOTED", suggesting that the man in the picture had been promoted to replace the fired poster. This was later shortened to "PROMOTIONS". In reality, of course, if you're caught browsing 4chan at work, you're probably going to get fired regardless of whether or not the page had nipples.
The meme itself is typically seen as a cry of "PROMOTIONS!" in response to an NSFW picture, or else some similar comment suggesting an improvement in the corporate status of the poster (such as "Company car!"). It is typically accompanied by an image of celebrating white-collar workers or someone in the same pose as the iconic promotion guy (pictured on the right), the image most strongly associated with the meme.
The meme doesn't show up on /tg/ as much as it does on other boards, mainly because
we like to think that /tg/ is capable of self-restraint in terms of spewing catchphrases. You're probably going to get banned for posting anything that could cause PROMOTIONS.
Ironically, this article has a curious lack of PROMOTIONS. The fact this page doesn't have PROMOTIONS is a serious problem.