I think that you are hiding something in your stomachs.

Je pense que vous cachiez quelque chose dans tes estomacs.

^did I use the subjunctive correctly?

I answered this one last night. That IS the Subjunctive form of cacher. The verbs penser and croire use the subjunctive when used negatively or interrogatively, but my question last night is WHY with the affirmative in this sentence?

Sra (aka Mme)

You don't use the subjunctive here.

"Je pense que vous cachez quelque chose dans votre estomac."

Penser is one of those French verbs which require the indicative mood when used in a declarative statement, but the subjunctive when used in a question or negative structure. The reason for this is that when a person says "Je pense que..." whatever comes after que (the subordinate clause) is, in that person's mind, a fact. There is no doubt or subjectivity. However, when someone says "Penses-tu que..." or "Je ne pense pas que..." the subordinate clause is no longer a fact in that person's mind; it is questionable or doubtful. Compare the following examples:

Je pense qu'il est prêt.
I think he's ready.

Penses-tu qu'il soit prêt ?
Do you think he's ready?

Elle ne pense pas qu'il soit prêt.
She doesn't think he's ready.

No, your use of the subjunctive in the French sentence is not correct. The correct form would be "Je pense que vous cachiez quelque chose dans vos estomacs" (with the subject "vous" and "vos" instead of "tes," assuming you are addressing multiple people).

To determine whether to use the subjunctive in this sentence, we need to consider the verb and the context. In this case, the verb "penser" (to think) does not trigger the subjunctive by itself. However, if there was doubt or uncertainty regarding the existence of something hidden in the stomachs, then the subjunctive might be used. For example, "Je ne suis pas sûr/e que vous cachiez quelque chose dans vos estomacs" (I'm not sure if you are hiding something in your stomachs).

Remember to analyze the verbs and context to determine when to use the subjunctive in French sentences.