If you don't know the name for something, just call it a hattifnat. Shouting hattifnat really makes people angry, so you can use it to annoy them. Example: Don't lie to me, you hattifnat! OR I saw this strange animal, but I don't know what it was. Probably a hattifnat.
HATTIFNAT
Meaning of HATTIFNAT in English
Slang English vocab. Английский сленговый словарь. 2012