Sensual petting in a dark movie theater will add some spice to your relationship and for a while will make you feel like high school lovebirds again.
It is advisable to choose morning, night or other not very popular shows and get tickets to the last row.
Start with touching — put your hand on your partner’s knee and slowly move up, stroke the partner’s inner thigh. Kiss passionately and then put your hand into the fly/panties and caress the genitals. If you are not alone in this theatre, try not to let people understand what’s going on between you two.
Do not move from petting to something more serious — cinemas have video surveillance, and sex in public places can still be subject to administrative liability :-(