Strč prst skrz krk
The sentence is well known for having a total absence of vowels, the nucleus of each syllable being a syllabic r, a common feature amongst many Slavic languages. It is often used as an example of such a phrase when learning Czech or Slovak as a foreign language.
In fact, both Czech and Slovak have two syllabic liquid consonants, the other being syllabic l. (There is also the syllabic bilabial nasal m in sedm in Czech.) As a result there are plenty of words without vowels. Examples of long words of this type are scvrnkls, čtvrthrst, and čtvrtsmršť, the latter two being artificial occasionalisms.
There are other examples of voweless sentences in Czech and Slovak language, the longest one being "Škrt plch z mlh Brd pln skvrn z mrv prv hrd scvrnkl z brzd skrz trs chrp v krs vrb mls mrch srn čtvrthrst zrn."