"SOMS" is a expressional acronym in the tradition of "LOL," "LMAO," or "ROTFL." Translated, the acronym means "Spat On My Screen." This term is used to denote that something received or viewed via electronic communication is so funny that the proverbial "drink in your mouth" would be ejected onto one's computer monitor.
"SOMS, LOL, LMAO. That email was so funny yo."