Can you say 'Can you keep it real' at an interview?

I would say it depends on the company and who you're interviewing with! In some cases, using this phrase and similar, more trendy phrases can portray you as someone who is up-to-date and fresh. But you better be sure to have the professional skill set and knowledge to back something like that up. In other cases, some companies or interviewers may see that as immature or unprofessional. Read the environment, but better to be safe than sorry. Professional is always the best way to go.