Invented in 2007 by a group of co-workers from the western Chicago Suburb of Wood Dale, IL, Mustache De Mayo is often abbreviated to "MDM". Mustache De Mayo is a celebration of May 5th by proudly displaying hair on your upper lip for just one day. To achieve the maximum unveiling of the mustache, a full beard or goatee must be grown in advance. Most often than not the MDM participant will create a persona and dress up in a fashion that suits the "stache".

A buzz word being used to refer to creators and influencers forming or encouraging unhealthy relationships with their fans. Usually used in the context of young audiences feeling they have a relationship with the influencer due to the huge amount of the influencer’s content they consume. The influencer in question, however, is unaware of the fan’s existence other than the general knowledge of having fans. Common examples include Dream and his stans. These relationships are exacerbated by the influencers confirming they have more than a creator-to-viewer relationship.

The word is circulating due to various YouTube essays about the phenomenon using the word, and therefore people who enjoy complaining about influencers repeating what they heard in the video in any comments section they can find.