Final answer:
If you see co-workers socializing outside of work, joining them during a break is acceptable, and some small talk is normal. However, long conversations during work hours are not professional. When people react to non-normative behavior, such as wearing pajamas to the grocery store, they're employing informal sanctions.
Step-by-step explanation:
If you see your co-workers socializing outside of work hours, the best course of action would generally depend on the context and your relationship with them. If it is during a work break and you see co-workers outside of the store enjoying a coffee or lunch, it could be acceptable to join them for informal conversation. It's usually seen as a normal part of workplace culture to engage in some small talk and socializing in appropriate settings such as breaks. However, it's important to remember not to engage in long conversations during office hours as that could be viewed as unprofessional.
Regarding personal boundaries, if colleagues share personal information, you have the right to set the level of intimacy you're comfortable with. In case the conversation turns to uncomfortable subjects, you can change the topic. Being aware of and respecting cultural differences is also crucial in a professional environment.
When it comes to people's reactions at the grocery store, whispering and giving strange looks because someone is wearing pajamas would be considered an example of informal sanctions. These are societal reactions to non-normative behavior that are not officially enforced but act as a form of social control.