SPOILERS AHEAD
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To unlock the striptease with Nick (as of Build 0.10b): Looking through the code, you need to have a relationship score with him of 20 or 25, and a not so great score with Mayhew. To get that, pick "Resist" at the end of Chapter 3, then in chapters 5 and 6...
"Why Me" or "Make an Appointment" at opening of Ch 5 (0 points); then "Act Normal" or "Self-Deprecating" joke (+10); "Avoid the conversation" (0 points); "reject the feeling"; invite him to use the spare bed (+10 points). That should keep the score with Mayhew low and get you 20 points with Nick to unlock the striptease.