not be sb's cup of tea = if something is not your cup of tea, it is not the type of thing that you like!

When we say that something is not our cup of tea, it means that we do not like it.

Examples:

Sci-fi is not my cup of tea. I prefer to love stories.

Thanks for inviting me, but ballet isn't my cup of tea.

Football? Ah... em... I don't really like football... And, it's gonna be too hot. Thanks. But sorry. It's not my cup of tea.