The Blabbermouth Curse

You attempt to charm a humanoid you can touch. It must make a Wisdom saving throw, and does so with disadvantage if you or your companions have captured it. If it fails the saving throw, it is charmed by you until the spell ends or until you or your companions end a conversation with them. The charmed creature is compelled to tell the truth. The creature must answer any and all questions with some level of truth. Half-truths and misdirections are allowed, but an outright lie is not. A creature may attempt to speak in a different language or silence themselves in order to prevent speaking. The spell does not affect their mentality or their perception of the world, and they are still allowed to speak of their own volition, unaffected by the spell.

A liar may use a dip in the conversation to speak their mind and twist the truth under the guise of the spell. The spell only forces them to tell the truth when asked a question, not throughout the entire duration. 

ENCHANTMENT/CURSE SPECIFIC:
This spell can be infused into non-magical items to make them magical. Items such as rings and necklaces when worn cause you to go under the effects of the spell without the wearer's knowledge. However, they are allowed to make Wisdom saving throws every hour under the effect to identify the source of the effect (the cursed item). When imbued into an item that can't be worn, it has to be making physical contact in order to trigger the effects of the spell. When placed in clothes that are being worn, it counts as touch. The effects of such an item are effectively the same as the above description.