1. " Go picnic" or " Go picnicking"? 2. "Go on a picnic" or "Go for a picnic" Thanks for your help! I helped my friend correct her mistakes in a homework video. She said: " I like going to the picnic". I knew it's wrong. So I changed it into " I like going picnic".
However, I've seen a lot of structures like Go + V-ing ( Go swimming, Go roller-skating, go fishing,...).  And now, I start to doubt my answer. " So it's "Go picnic" or " Go picnicking"? 
By the way,  may I use "Go on a picnic"  and "Go for a picnic" to express the same idea? 
Thank you!