Jennifer Lopez Surprises Fans at The Boy Next Door Screening in Miami

Fans attending a screening of Jennifer Lopez's new psychological thriller, The Boy Next Door, were in for an unexpected thrill – an appearance by J.Lo herself!

After a busy weekend turning heads – including her co-presenter Jeremy Renner's – at the Golden Globes on Sunday, Lopez headed to Miami to give her fans a special surprise.

The screening, presented by the J.Lo-endorsed health and fitness brand Bodylab, took place Tuesday night at the CineBistro in Miami.

The movie ended, the lights came up, and moderator Pamela Silva Conde, co-anchor of Univision’s "Primer Impacto," announced that J.Lo was in attendance and would be treating the audience to a Q&A.

The 100 or so attendees went "absolutely nuts," an onlooker reports to PEOPLE. The surprised fans shouted Jenny's name and whipped out their phones.

During the Q&A, Lopez commented on the film's rapid schedule, telling the audience that filming in just 23 days on a "micro budget" of about $4 million was quite a different experience than her other 30 films.

When a fan asked Lopez how she manages to maintain her amazing figure as a mom with such a demanding schedule, the star noted that it is all about balance and although there is no "solution in a bottle," she does start every morning off with a Berry Berry Good Smoothie from Bodylab.

Next on the triple threat's agenda? Lopez and hunky costar Ryan Guzman will host a marathon of Oxygen's Snapped on Sunday, Jan. 18th.