I like disadvantage. Let’s make this happen in Pathfinder
Casting Time 1 standard action
Components V, S, DF
Duration 1 round/level
Saving Throw Will negates; Spell Resistance yes
Touching the target with your holy symbol, you ask your god to curse the subject before you. The target must roll two dice on the first attack roll (weapon or spell) it does each round while under the curse. At the end of each of the creature’s turns while affected by this spell, it may attempt a new saving throw to end the effect. This save is a free action. If this save is successful, the effect ends. If not, the curse continues on the creature continues laughing for the entire duration.