Lethal Weapon/Nightmare Fuel

Most Notably:
 * Pretty much any scene where Riggs is pissed off at someone or suicidal.
 * In the first movie when he breaks free of his Shock Torture, before going after Joshua. Earlier on when Murtaugh didn't take his suicidal tenancies seriously until he almost shot himself.
 * The second movie when he finds out that not only  This troper originally considered that moment to be a Tear Jerker, but after what Riggs did to them afterwards....