When the aliens inevitably come down in the far, far future to explore the ruined remnants of our collapsed civilzation, I'm pretty sure these are what they'll use to piece together our culture. 

1.

emotions

via questionsgalore55

2.

mms

via sleclercjr

3.

lacrosse

via TeamSubie

4.

statue

via sporks49

5.

train

via ReallySadNipples