(be) under the impression that... phrase
One believes that something is true, but in fact, it is not.
I was under the impression that I had met that blond girl somewhere.
I was under the impression it was him who stole my purse.
Many people are under the impression that drinking some wine before going to bed can improve sleep.
The speaker uses this phrase to admit that he or she has learned something by an unconventional way.
Daughter: So I really want all my friends to have a great time. I was thinking it would be a good idea to have some candy out on the tables for people to snack on.
Mother: Well, if you want them to really enjoy themselves, candy is dandy but liquor is quicker.