I dont know it was shared in Warrior Forum or Not. But its really a good way to post in many group at a time. Lets Start the Process:
What to Do:
1. You must have to be Group Member.
2. You have to know the Group Email ID.
3. You have to use your email which is your facebook login email.
Now How to Find the Group Email:
If the Group URL is https ://www.facebook.com/groups/abcxyz group email id should be firstname.lastname@example.org
How to post in many Groups:
Go to your email & write down the text what you want to post in Group. Then Send to 5-10 Groups email at a time. If you want to post in 50 Groups then do this 5-10 times. But dont spam it may ban your account.
It may not works for every groups, I tried for 20 Groups But It was posted in 18 Groups. Dont Spam.