Take another look at the sentence:
Abdullah gasped as the badly wrapped burrito squirted its contents onto his shirt, which was spicy hot and full of lettuce.
Which was spicy hot and full of lettuce, a relative clause, comes right after shirt, an illogical target. The burrito, not the shirt, is spicy and full of lettuce!
Before you continue, review the rules for misplaced and dangling modifiers.