In the reptile house using my Canon 100mm macro lens. A customer at the photo lab I work at gave me that lens a couple months ago because he bought the new upgraded version (L series). I have never enjoyed photographing reptile houses as much as I did on this trip with this lens.
Of course it also meant my camera bag increased in weight by going from three lenses to four lenses - just when I was trying to figure out if there was any way to cut back from three to two. Still, I cannot complain. I am sure there are many people on this forum who wish they had the "problem" of people giving them prime Canon lenses!