Hi melissa09,
Code:
I know what you are talking about.
It sounds as though you have been doing some deep soul searching and perhaps it shocked you when you found yourself laughing at something that was crude. I don't think this is mortal sin, but I would confess it anyway, just to be sure. I think it seems you are remorseful, since if you weren't, you would not be concerned enough to ask the question. So I would say it is a sin, but probably venial. Just try and keep remembering to always put Christ first ahead of you in everything you do. Even with doing that, we are sometimes caught off guard. Sometimes I think that we laugh as a reaction to others laughing too- so don't be too hard on yourself. You recognized it was offensive to God and that is a good start. You can always speak with a priest about it, and I recommend that since I am not clergy.
I would doubt that it is mortal unless one would have an ongoing careless attitude about it. Some people might think I am making a big deal about it, but laughing at these things is a tiny way that we can slip further into other larger sins and this can lead to a nonchalant attitude about our spiritual life. …(and that means further from Christ

Why take that risk!!!

) I say that more for other readers than for you, melissa09, I think you already have realized this.
There is a rule of thumb that gets passed around that helped me greatly when I heard it. It goes something like this:
If you can’t imagine Jesus and Mary sitting with you enjoying a tv program, listening to a certain song or radio program or any type of entertainment for that mater, then that means you probably should not be viewing/listening to it yourself.
I am also reminded of Philippians 4:8 (New American Standard Bible)
Finally, brethren, whatever is true, whatever is honorable, whatever is right, whatever is pure, whatever is lovely, whatever is of good repute, if there is any excellence and if anything worthy of praise, dwell on these things.
Ask yourself, are the tv programs you are watching describe what is listed above? If not, make amends!! You will be glad you did!
As for the question of when will we have control over our laughter… We are to grow in our spirituality in Christ and that takes time, prayers and God’s grace. Keep seeking! God is true to His promises! Alleluia!
May God Bless you!