Can Ca and K exist as an ionic compound?
As a creator of this memetic illustration, I feel obliged to post a brief answer.

Potassium is known for forming several metal alloys, such as a widely used Sodium-potassium alloy NaK.
However, CaK doesn't exist [1]:


  The Ca-K system was found by Klemm and Kunze [67Kle] to exhibit virtually complete immiscibility in both solid and liquid states. No compounds were found by X-ray diffraction. 
  
  Cited Reference
  *67Kle: W. Klemm and D. Kunze, "Systems of Alkali and Alkaline Earth Metals," Proc. Int'l. Symp. on Alkali Metals, London Chem. Soc., Special Publ. No. 22, 3-22 (1967). (Equi Diagram; Experimental; #)


References


Pelton, A. D. The Ca−K (Calcium-Potassium) System. Bulletin of Alloy Phase Diagrams 1985, 6 (1), 34–34. DOI: 10.1007/BF02871178.