The actress was asked by American Glamour in a hilarious video interview: "What secret would you like to know about a potential date?"
She laughed and looked off camera before a producer said: "I know where you went" as a cartoon of a ruler popped up on the screen implying a man's size is important.
Related articles
Jennifer replied: "Yeah. Because it's a gamble, it's always a gamble. You don't know."
The 25-year-old answered a series of other questions in true J-Law style.
When asked what her signature scent was she joked: "Red wine. I smell like a Cabernet."
She also told fans how to make her best food invention – the chilli pizza sandwich.
Jennifer instructed: "A piece of pizza and then you put chilli in it - like Southern chilli, with noodles - and then you put another piece of pizza, and then you eat it like a sandwich."
She sarcastically suggested that she wasn't under the influence when she invented the sandwich: "I was completely sober. Totally sober."
The star stripped off for this month's issue of the magazine, in which she admitted that she's got "t*ts and an ass" so can't dress like "skinny girls".
Jennifer flaunted her enviable figure in the shoot as she posed in a black bra and matching high-waisted briefs.
However, while she may be one of the hottest actresses right now, the Joy star revealed she does still have insecurities.