Well you can try to just play one opening, but of course your opponent has something to say about that. It's not a bad idea though to find an opening you like and play it as much as you can. Learn it thoroughly enough to the point where you're a little bored with it and then move on.
choosing an opening
Play an opening if you like playing it, don't if you don't. Chess is a pastime (for 99.9% of players) and as such it is meant purely to be enjoyed!

is it ok if i play just one opening all the time?
i don't like playing the sicilian defense is that ok?
because so many people play it and i don't want my opponents to laugh at me i could not play it
The most inportant things is to have fun! Its a game. Play as many or as few openings as you want, but find openings you enjoy playing. I play 1 as white, and 2 as black, and they have served me well.
is it ok if i play just one opening all the time?
i don't like playing the sicilian defense is that ok?
because so many people play it and i don't want my opponents to laugh at me i could not play it