The first three ones only

Hello everybody. I´m a little bit lazy today [Maybe because is friday] and that´s why I come to you guys xD

I was wondering how can I make a selector that lets me show only the first three <li> elements of an <ul> element, on the ready() function ??

You can suppose that the <ul> [More than one] has a class or are accesible via his parent or sibbling xD