Laughter is a good physical release & releases endorphins & other pleasant chemicals into the brain.
There are healthier ways to go about this other than suicide hotline pranks. Pranks to a serious agency take up the counselors time that could be used to save the life of one truly in need.
Look at funny movies/shows on tv, comedy channel is good medicine, rental of comedy videos from standup to movies, bloopers on tv, funniest videos, etc. Those are healthier for you and do not tie up suicide lines. If you enjoy pranks, there are plenty others that do not focus on life hanging in the balance.
Moreover, looking at funny vids should be supplemented by professional support in the mental health field. Funny vids might stop u at that moment, but exploration of the cause for the suicide decision should be explored. Proper counseling and sometimes medication can save your life. I suggest you see a doctor for an evaluation.
If you are currently receiving psychological support, meet w/your doctor or team because it sounds like changes need to be made in your treatment regimen. This desire might fleetingly pass, but the reasons for thinking about it still exist.