Concept for 'too much exposure to a bad idea can make it seem normal'? I wanted to know if there was a studied concept/term for the notion that too much exposure (in terms of sensory stimulus) towards a bad idea/thing (eg. say drinking) in a normal connotation can make the idea look less bad and more normal.

Eg. If a person keeps getting a lot of jokes etc. on a group chat (say, Whatsapp) or in his/her Facebook feed etc. about getting drunk, and the jokes are somehow glorifying this behavior (eg. 'I am an introvert, but when I bring in the drinks, I attract everyone' (I know, bad joke)). So getting a lot of such input toward a hazardous behavior may entice a not-so-heavy drinker to go full blast, because (s)he may start thinking that this is very normal and probably even fun. This is just an example, this can be thought for many other hazardous behaviors.  

So my question is that has such behavior been studied, and is this somewhat true?
Are you thinking of desensitization?

From wikipedia: In psychology, desensitization is defined as the diminished emotional responsiveness to a negative or aversive stimulus after repeated exposure to it. (https://en.wikipedia.org/wiki/Desensitization_(psychology))

Desensitization seems to match the question as posed in the title, but maybe not the question as posed in the text.  Desensitization occurs based on mere repetition.  In the body of the question, it seems like you're referring to repetition that takes place in the context of otherwise normal (non-negative or aversive) context, so that the once-negative subject acquires some of the normalcy of the context.