The periodic symbol for sodium is Na, while hypobromite is a chemical compound denoted as BrO -. Together, the compound sodium hypobromite is NaBro, or in this case, “No, brother”.

“Pusheen (pushing) the limits of lab safety”.

In chemistry, individuals use a technique known as titration, in which a known solution (titrant) is used to determine the concentration of solution that is under analysis (analyte). In a famine, a populace is provided rations, and in this joke, the chemist receives titrations.

Instead of remaining nitrogen (“night”rogen), it becomes “day”trogen when the sun rises. The rest of the words simply rhyme with the common bedtime saying: “Good night. Sleep tight. Don’t let the bed bugs bite.”

The periodic table of elements we arranged to form a Christmas tree with 3 presents of holmium (atomic symbol Ho) placed under the tree.

NMR spectroscopy, or nuclear magnetic resonance spectroscopy, is a method of research used to define the physical and chemical properties of atomic nuclei. Bar magnets are a type of magnet, and for this joke, the reference to lawyers alludes to the legal term “bar”, which is the name of their professional association and examination for licensure.

Chemists work in laboratories. Labrador retrievers are a popular dog breed, hence, “laboratory retrievers”.

Amphetamine is a synthetic drug with the chemical composition C9H13N. "A feta meme" is a humorous image of feta cheese that can be rapidly spread throughout the Internet.

The periodic symbols for the elements are as such:

• Oxygen = O
• Hydrogen = H
• Sulfur = S
• Sodium = Na
• Phosphorus = P

OH SNaP!

Instead of a peanut butter (Pb) and jelly sandwich, the joke refers to lead, which is denoted by Pb on the periodic table of elements.