Every time I see this expression I think of the time a woman I was seeing pulled a doughnut off the table beside my bed and started eating it before we went to sleep at around 1-2 in the morning. She had picked it up earlier from Tim Horton's and not eaten it. She finished eating it, turned out out the light and rolled over to go to sleep. I couldn't let it go and asked if she was going to brush her teeth post-doughnut. It led to a massive fight and she went home.
All that to say, I've never kicked someone out of bed for eating crackers, but I have kicked someone out of bed for eating a doughnut.