The word "sneakthiefs" is not a correct spelling in English. It seems to be a combination of "sneak" and "thief". A more proper spelling would be "sneak thief". The IPA transcription for "sneak" is /snik/ and for "thief" is /θif/. The suffix "-s" is pronounced as /s/ in this case. Therefore, the correct pronunciation of "sneak thief" is /snik θifs/. Always check your spelling to avoid creating an incorrect word.