Our teacher wore a t-shirt with red lettering that read "if what you're reading is blue you're running to fast" and asked us to find out what it means. Any body have a clue, I was wondering about doppler.

yep

red is low frequency, violet is high frequency

If you see a shift from red towards violet, the radiator is moving toward you fast so you see a higher frequency than the radiator radiates.
If you are standing at a train station as a train goes by making a noise, you hear a high frequency as it approaches and a lower one the instant it passes and starts moving away from you.
The T shirt person was not only moving fast but also was headed for the teacher.
In astronomy, the red shift means that the light we see from a start is shifted toward lower, red, frequency because it is moving AWAY fast.

The phrase on your teacher's t-shirt, "if what you're reading is blue you're running too fast," does not directly relate to the Doppler effect. Instead, it seems to be a play on words and colors to convey a deeper message.

To understand the meaning, let's break it down:

1. "If what you're reading is blue": The color blue is often associated with sadness or feeling down. In this context, it could mean that if what you are reading makes you feel sad or unhappy, then something might be wrong.

2. "You're running too fast": Running too fast metaphorically suggests rushing or moving through things too quickly without fully comprehending or digesting them. If you're constantly rushing through your reading, you're not taking the time to understand the content properly.

So, when combined, the phrase could be a reminder to slow down, take your time, and fully comprehend what you're reading to avoid negative emotions or misunderstandings.

Regarding your mention of the Doppler effect, it doesn't directly relate to the phrase on the t-shirt. The Doppler effect is a phenomenon observed in waves, such as sound or light, where the frequency of the wave appears to change relative to an observer as the source of the wave moves closer or farther away. It is not directly connected to the concept conveyed by the t-shirt message.