The expression is actually, "This IS going to blow your mind." It is the same as saying, "You are going to find this so amazing!" It's not a rude thing to say, but you usually only say it around friends. Salesmen usually say it to make it sound like their products are the latest invention that will surprise and awe you. I usually say it to girls on the second or third date. People's minds rarely get blown.

yes i know exactly what this mean s because i use it. the phrase the phrase this gonna blow your mind- means watch this, watch what i can do! i am going to do something to impress you. so if you were to do a trick on a skate board you would say hey , watch this to get your friends attention. you would use this phrase with your friends in a casual joking, relaxed setting. never in a presentation or work enviroment.

Understand ''blow'' as ''explode''. This is so amazing your head will explode. There's no rude innuendo here. By the way, the phrase is ''This IS gonna blow your mind.'' Missing ''is'' is simply wrong, even in slang speech.

It just means you will find this totally amazing