2.A strange amusing noise that can be heard by everyone but the maker. The noise usually occurs when the maker believes they are not talking. The maker of this noise is usually quite offended or surprised and they deny making such odd sounds.
3. A fictional noise people pretend to hear to bother those who cannot hear it.
2."Hey Jessie you made caterpillar noises again" "No Anneka shut up I did not make caterpillar noises they don't exist" "Yes they do" "You suck"
3."Hey did you hear that catepillar noise, Jazza?" "No Desmond wait catrpillar noise?" "You can't here it?" "Umm I'm worried now"