At least you won't be hearing that anymore. Hopefully you'll find a better gf.

That was your guinea pig making noise op. He kept trying to tell you.

I just want to know how your girlfriend was over and you didn't notice? Does she sneak in and out of windows? Invisibility cloak? Does she have a twin and you just thought it was her sister?

How did you miss that? Surely you would notice her coming to your house/ leaving your brother's room?

I usually dont condone violence, but they both need to be punched SO HARD in their respective reproductive organs. Repeatedly and without mercy. Dump the bitch and kick your brothers ass everyday for a year.

At least you're not getting cheated on anymore.

Two things to do. 1. Buy a pregnancy test. Use a blue pen to make it look positive, put in the trashcan in your brother's bathroom or the shared bathroom. Make sure he'll be home before she is and that it looks badly hidden. 2. Buy a bra. You can get one for a few dollars at Big Lots and other bargain stores. Crappy bras, but, hey, it only has to LOOK nice. Make sure it's not a small bra, nor a white one. Go for a bright red or black lacy one, and at LEAST a D cup. Remove all tags. Put that somewhere that she will see it, such as barely sticking out of a pile of laundry or from behind brother's bed. They each know the other one is dishonest and cheats. This should be a great amount of fun to watch when the drama unfolds. Best to put the pregnancy test out, then let them scream at each other for a week, THEN hide the bra. She'll be sure he's found someone else that isn't pregnant. And just feign total ignorance as they try to fight about this w/out you finding out.....

Set the bed on fire.

Or or or it's the brothers bed squeaking.

Three months? Time to dump the girlfriend and go at war with your brother. Good luck. (Don't forget to beat the crap out of him)