Mysterious White Box

For two days there was a strange wooden box sitting in the middle of the sidewalk in front of our neighbours house. I barely paid any attention to the box until this morning. I became extremely curious/concerned when I noticed the spay painted stencil on the box this morning. It read: "Contains secret test samples. Do not disturb box." Now the box is gone and I've missed my chance at taking a picture (to give you all proof).