Green Japanese Signs

I was just plurking around when some of my friend plurker (Amcel Ong) shared a photo with a message: "WAAAAT?"

Duh,. I'm curious that's why I clicked on it, and here it goes:

So. What comes on your mind now? Hahaha!
For me, the first thing that comes on my mind is that: (From Left to Right)
1. A boy who feels so horny, his dick errected.. as if he can't take it anymore..
2. So what the boy did~ go fucked her woman doing some sex position..
3. After he come out~ the girl got pregnant
4. Then, finally... that girl gave birth to the child.

Ugh.. I think we have the same impressions huh? But the real meaning of these signs were:

According to Amcel: these are signs in Japanese Metro Trains,
'Priority seats for ................', From left to right:
1. Person with injured arm
2. Person holding a child
3. Pregnant woman
4. Person with injured leg

Funny huh?