"I just have to work another late shift." Check to see if he's working on a large undertaking that you can independently verify. If you can't, then challenge yourself.
"You have my lipstick on my collar." This is the most blatantly false untruth he can tell you. Look at the makeup.
You're the one who gave me that hickey." You presumably don't give hickeys on a regular basis because you're not in high school.
"I'm just going to watch at the strip joint." Nobody goes to a strip club just to observe naked women gyrate on a pole.
"No, I'm not a fan of internet porn." I'll paraphrase Avenue Q and say that the internet is fantastic... for erotica.
"I do not masturbate." In the shower, every single guy jerks off. That, along with shaving your face and growing leg hair, is part of being a male.