Question Summary:
Does Ghusl become Wajib on me if I feel wetness after having thoughts?

Question Detail:

sometimes in my mind came bad thoughts and after that i feel wetness in is ghusul becomes wajeb for me?

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
The wetness you refer to is Mazi. Mazi is impure and invalidates Wuzu. Gusl does not becom compulsory through the emission of Mazi[1]
 
 
And Allah Ta’āla Knows Best
Immad Bin Arshad
Student Darul Iftaa
California, USA
Checked and Approved by,
Mufti Ebrahim Desai.
www.daruliftaa.net