Friends crossing the line - sexual propositions 

The other night I was quietly minding my own business, watching LCS and drinking cold drinks, basically chilling in the summer heat, when I got a call. The call was from a friend, a drunk friend. Said should be, is that I´m an easy going person, I like to joke around and not take things to seriously. However, this friend fully stepped over the line, and said something that not only pissed me of but also gave me a really uncomfortable feeling. I understand friends getting a bit drunk and wanting to joke around, but to in detail describe what the person in question wanted to do with me in an adult way, was not okay in any way. I have zero tolerance for this and will not likely ever speak with this person again.
Lastly, why do people get so intoxicated that they don´t know any more how to behave?