The lodgers were initially amused when they saw Gregor.
There were 3 lodgers. The middle lodger was the one who noticed Gregor first. He merely called out Mr. Samsa's attention and pointed his index finger to Gregor. He and his friends seem to find Gregor amusing. However, when they were being ushered by Mr. Samsa out of the living room and into their rented rooms, they became irritated and demanded an explanation from the family.