clumsy, foolish, unattractive, or otherwise unintelligent act or person.
derp, derp face, herp derp, hurr durr
Derpy is very commonly used as an adjective to describe someone's clumsy or foolish behavior, occasionally that of the speaker themselves. Sometimes it is used as a direct replacement of the r-word.
It is also used to describe someone else's physical features as unattractive or akin to someone with intellectual and developmental disabilities. In imagery, derpy or a so-called "derp face", is often signified by crossed eyes, a stuck out tongue, or permanent facial differences.
The word "derp" found its first known use in the 1998 film Baseketball by the creators of the American animated sitcom, South Park, and later in South Park itself in the name of the character "Mr Derp". The creators of the show have expressed that the term is uttered when one "screws up". In these early uses the word is interchangeable with the words "duh", "hur" and "dur" that came before it, and may have directly or indirectly originated from them.
The word evolved in 4chan and other forums and began being associated with memes, where the "derpy" imagery began. It is there where it became associated with intellectual and developmental disabilities (I/IDD) specifically, as people started overlaying "derp" over photographs of children with I/DD.
Regardless of whether derpy is being used to describe yourself, or someone with or without an I/DD or physical disability, use of the word contributes to the dehumanisation, stigmatisation, and negative perceptions of people with an I/DD or physical (especially facial) differences.
By using ableist language, we are perpetuating violence against people who experience mental, developmental, or physical disabilities. Using this language perpetuates those systems and language of harm, regardless of our intent.
Be more specific. Typically we can find an alternate definition by taking time to reflect on what emotion we're really feeling. If you are describing a person's silly actions or expressions use a more relevant, descriptive word.
If you are using it to describe or refer to a person's disability or physical difference, don't.