In English, there are no words that have only voiceless sounds, since all words in English have vowels and vowels in English are voiced. (There are noises that English speakers can make which are all voiceless, like "shh!", "pst!", but these aren't words).
Some languages have words without vowels, such as Bella Coola (Nuxalk) and some dialects of Berber. For example in Bella Coola, [xłp̓χʷłtłpłłskʷc̓] is "then he had had in his possession a bunchberry plant". In Tashlhiyt Berber [tftktstt] is "you sprained it (fem.)". There are languages with phonetically voiceless vowels, such as Japanese and Comanche, but from what I can tell, no word of Comanche can be composed of only voiceless segments. Tsuchida (2001) notes that in Japanese you cannot devoice two vowels in a row, so every word has at least one voiced vowel.