Out of 31 designs
7 (23%) portray rainbows as some manner of science or technology related phenomenon.
17 (55%) portray rainbows as some form of bodily fluid or other waste.

Specifically,
8 (26%) portray rainbows as vomit,
2 (6%) portray rainbows as flatulence,
3 (10%) portray rainbows as feces,
1 (3%) portrays rainbows as urine,
1 (3%) portrays rainbows as nasal mucus,
and 2, (6%) portray rainbows as blood.

Science:


Space Ships (and stations):


Vomit:


Farts:


Poop:


Pee:


Snot:


Blood:


Non-bodily fluids expelled forcefully from body:




Other:


FROM THE CRITIQUES:
teapots
another vote for blood