Do you say "cheesy" when someone's flirting with you saying pickup lines?

Native speaker’s answer
Rebecca
"Cheesy" or "corny" is used to describe something that may seem overly sentimental or even unoriginal/insincere because they are so commonly said. For example, popular pickup lines (as you mentioned) can be said to be cheesy if they are overly sentimental and seem insincere with how common they are. Of course, it depends on context. It can be meant positively, depending on tone and situation (like if you are joking around with friends). Ex: A guy tried to pick me up with the cheesiest line. Ex: You guys are my best friends. It may sound corny, but I mean it.