Hanging yourself or shooting yourself in the face are the classiest options available IMO.

i want to get a time machine and go back in time a couple seconds to stop myself from going back in time. therefore, i never went back in time, meaning i never stopped myself from going back in time, meaning i did go back in time, meaning . . . and this paradox would probably kill me.

Running around drunk senseless in a violent lightning storm, wearing nothing but pure copper nipple piercings.
...That sounded much sexier in my mind.

I'd wanna die in a knife fight with only me and my opponent left in the world, and when I'm finally stabbed in the chest, I stab him back as a last stand, leaving us both dead on the ground.
If I can't live nobody can >:3