She randomly appears when you access Londog's bio.
You mean the "So Far So Familiar" achievement or the secret profile image for DJ Scratchy?
If it's the latter, then it's also random chance.
If it's the former, you need to place down the following characters:
- B.A.K.D.G (Beat 1)
- Signy (Effect 1)
- DJ Scratchy (Effect 2)
- Mustard Man (Voice 1)
- Matty "Stampeedy" (Voice 3)