From joking about a colleague's sex life to casual butt-pinching, businesses are rife with sexual harassment and pressure to eliminate it is mounting — but which behaviors cross the line?

While groping a workmate or showing them porn on your computer may be universally frowned upon, experts say sexual harassment can be difficult to combat because people have different reactions to others' behavior.

" 'No' means no, but there is a lot of room for error and embarrassment before you get to it," said Martin Sirakov, who works for a health care provider in London.