Last night Kendall Jenner celebrated her 18th birthday at Mastro's in Thousand Oaks her sisters Khloe and Kylie (along with with parents Kris and Bruce Jenner), and the ladies may have worn masks, but they weren't able to escape being asked about Kendall's reported porn offer!

Apparently the website Bangyoulater offered the now-legal reality starlet $1.8 MILLION to have sex with a partner of her choosing, according to TMZ. There are a handful of other porn sites that want to offer Kendall big bucks to get nasty, and Digital Playground even gave her the option of a lesbian movie with porn star Jesse Jane.

Kendall was able to keep a straight face when asked about the X-rated proposals, but Khloe got annoyed and told photographers that the questions were "inappropriate." Hey, seeing as Kim got her start with a sex tape, we think it's a pretty fair question to ask...