It seems like the only funny things found in textbooks back in the day were woefully inaccurate statements, totally outdated information and the occasional student added slogan or drawing.
Nowadays many textbooks look like they were slapped together without much forethought, and apparently they're also full of hilariously bad stock photos, (seemingly) unintentional sexual innuendos and situations which simply aren't very well thought out.
Calling a girl to get her phone number? Okay, whatever, but using a still shot from the hit TV show Community on the cover of your Organizational Behavior textbook- now that's crossing the line!