The phrase "unexpected guests" means people who come to visit you without any prior notice or invitation.
Sentences with «unexpected guests»
Made this last - minute for unexpected guests when I realized that I had chips... and nothing else. (smittenkitchen.com)
Include small backup gifts as part of your holiday hosting survival kit in case unexpected guests arrive or you're invited to a party last minute. (ftd.com)
We had a table here, as well, and had decent sales as well as a couple of unexpected guests. (fictorians.com)