Please don't use 'derp' with me. It's commonly used to insult disabled people, and uses perceptions of intellectual disability as a device to insult people. Unlike a lot of other ableist words (see: moron, idiot, stupid, dumb), it's not one which has a strong history in common lexicon, a defence often used for using them.
The emoji for example has eyes wide apart (common depiction of downs) and mixed with the word 'derp' it has ugly connotations.
I'll never be ok with it.