Salam quique, 1. I believe that منشن here was meant to be منشان and it equals the word عشان as well, these words are used in Levantine Arabic to mean: for/ to be able to/ because, so it really depends where they are mentioned in the sentence to understand the exact meaning of them. 2. I totally agree with Ahamd about the word لمّا because it's a Fus'ha word beside being used in our spoken accents, and in here as you mentioned it, it means: when.

when = لمّا but in real arabic it write " عندما " example : when i go عندما ذهبت \ لمّا ذهبت . ( لمّا = عندما ) in the spoken arabic and the word " منشن " it's an English word

When = لمّا we can say it in informal Arabic ,but عندما it's formal

If this post relates to comedy/parody accounts found on Instagram, twitter and other websites or applications,... it would mean: منشن = (Mnshn) = mention, normally given as a request to mention whom you can associate to the post. لما = When/Whenever,... used with parodies.

I agree with Abed and Alla, but I want to add that, لمّا is indeed a correct standard Arabic word, which means "not yet" (close to " لَمْ ") لمَّا يذاكر درسَه : لم يفعله إلى وقت الحديث Also " لمّا "-meaning when- is a clear standard word. " فَلَمَّا أَضَاءَتْ مَا حَوْلَهُ ذَهَبَ اللهُ بِنُورِهِمْ " For more information, check: http://www.almaany.com/ar/dict/ar-ar/%D9%84%D9%85%D8%A7/