You in the lab:
Running a “simple” experiment.
Brain: “Remember to label everything.”
Hand: Forgets to label anything.
Background music: Mission: Impossible theme intensifies
10 minutes later:
Staring at 5 identical tubes like:
Which one’s control?
Which one’s treated?
Why am I like this?
Now you’re not just a scientist.
You’re a biotech god guessing fate, assigning identity, deciding destiny. 
You:
“I think this one feels like Sample A.”
“This looks like something I would’ve pipetted first.”
“This is probably the buffer… I hope.”