A 'Bobby-laugh' nearly always follows a comment that is either mediocre in its comical value, or not funny at all. What seperates the laugh from a standard laugh is therefore defined post-joke; upon review of whether the magnitude of the laugh coincides with the comical level of the 'joke'.
The laugh is usually short, loud and abrupt and bares little justification.
This laugh is not of sarcastic tone and is usually intended as genuine by the laugher.
The enthusiasm and the magnitude, as measured by volume and abruptness, is often linked to the degree of compliance and agreeableness that the laugher wishes to demonsrate.
Person A: "...I don't know what i'd do with the money!!!?"
Person B: "...calm down love you still have a 2 more boxes left yet!"
Bobby Laugher: "...HAHAHAHAHA."
Note the bobby-laugher often is not included in the dialogue of the main parties concerned.