Ř
The grapheme Ř, ř (R with háček, example of Czech pronunciation: 
"řeka" ) is a letter used in alphabets of the Czech, Upper Sorbian, and Silesian languages. A similar consonant can also be found in some Norwegian dialects around Narvik and in Berber (especially in its Rif variety). However, of the official national languages, only Czech has it.[1]
The Unicode glyphs are U+0158 Ř and U+0159 ř . Either can also be represented using the combining character U+030C ̌ COMBINING CARON.
Usage
In Czech it is used to denote [r̝], a raised alveolar non-sonorant trill. Its manner of articulation is similar to other alveolar trills but the tongue is raised; it is partially fricative. It is usually voiced, [r̝], but it also has a voiceless allophone [r̝̊] occurring in the vicinity of voiceless consonants or at the end of a word.
In Upper Sorbian, it denotes the voiceless postalveolar fricative [ʃ].
Tongue twister
Czech: “Třista třicet tři stříbrných stříkaček stříkalo přes třista třicet tři stříbrných střech.”
Phonetically: [ˈtr̝̊ɪsta ˈtr̝̊ɪt͡sɛt ˈtr̝̊ɪ ˈstr̝̊iːbr̩niːx ˈstr̝̊iːkat͡ʃɛk ˈstr̝̊iːkalo pr̝̊ɛs ˈtr̝̊ɪsta ˈtr̝̊ɪt͡sɛt ˈtr̝̊ɪ ˈstr̝̊iːbr̩niːx ˈstr̝̊ɛx].
English: “333 silver fire hoses squirted [water] over 333 silver roofs”.