There is a catch to it
You're listening to Sound Czech - Radio Prague's Czech language series in which you can learn useful phrases through song lyrics. Today we'll be listening to the singer-songwriter Jan Spálený and his 1985 song called Asi v tom bude nějakej háček, which also happens to be the phrase we will hear today.
The phrase 'Asi v tom bude nějakej háček' literally means 'there is a hook to it'. The Czech word 'háček' is derived from the word hák, or hook in English, and as you can hear, these words have common origin in the of old Germanic language. English has a similar expression that says 'there is a catch to it'. The meaning is identical - something appears to be fine, nice and easy, but underneath, there is a catch. In this particular song, the singer is giving an account of his bad luck in life. No matter what he does or how hard he tries, he is unable to achieve peace of mind. There has to be a catch. Listen to Jan Spálený again.
Please note that the form of the word 'some' in this song is 'nějakej' rather than the proper 'nějaký'. In most parts of the Czech Republic, especially in Bohemia, this is how almost everybody would pronounce it in informal conversations. In Czech, there are several other ways of expressing similar suspicion. You can say 'něco se mi na tom nezdá' - literally 'something doesn't appear right to me about it', or 'je na tom něco divného'- there is something strange about it. The fraze 'smrdí to', meaning 'it stinks', is quite expressive you and should be perhaps more careful using it. It is more suitable for bank robbers, for example, or some other badly spoken individuals.
Czech also has a colloquial expression 'mít něco na háku' - literally 'to have something on the hook'. The person saying this is not announcing successful fishing, but rather the fact that they couldn't be bothered. Those of you who have some experience with the Czech language already know that the word 'háček' also refers to the diacritical mark called caron. It appears, for example, above the c in the very word 'háček'.