Soulja Boy & Crew -- Sun's Out, Handgun Out ... for Morning Turn Up

Soulja Boy and his posse started their day with drugs and guns and even flaunted it on the Internet ... which ain't the smartest move for a guy on probation.

Soulja posted several videos bragging about a wake and bake session at his house, but the one where his pal is waving high-powered handgun with an extended clip ... could get someone in big trouble.

Check out the video -- Soulja's sitting on the kitchen counter smoking while another guy stands behind him waving the weapon. SB lives in L.A., and in Cali it's illegal to buy a large capacity magazine (defined as more than 10 rounds).

Plus, Soulja is on probation for a weapons charge from 2014, so ... he's flirting with a violation.