They banged. Widow was on a mission to kill hawk eye and she wanted some info before hand so she banged him.
That's what happened in Budapest.
Are you happy?
So this doesn't explain Budapest but in the Avengers when you first go onto the helicarrier it shows a scene of Hawkeye and Black Widow fighting together which I assume to be Budapest
Story time!
Back in the day Widow was sent to kill Hawkeye, so she went after him, slept with him, but didn't kill him. Since she didn't do what she was supposed to do, people were sent to kill both of them, and they had to fight them off.
So in this scene, Widow is referring to the fighting, Hawkeye is referring to the sex.
That's what happened in Budapest.
Are you happy?
Or are you makin' this up?
Back in the day Widow was sent to kill Hawkeye, so she went after him, slept with him, but didn't kill him. Since she didn't do what she was supposed to do, people were sent to kill both of them, and they had to fight them off.
So in this scene, Widow is referring to the fighting, Hawkeye is referring to the sex.