I would add the word "all" before "over" to add some dramatic flair to the sentence: He made me so angry that I knocked my lunch all over his crotch. // Or --> He made me so angry that I intentionally spilled my lunch all over his crotch. Crotch tends to sound like a lower, informal, register, so I would not use it with strangers. If you don't know your listeners that well, I would use the word "lap" instead of "crotch".

The sentence is correct grammatically, but the verb usage could be improved. The wording implies the act was intentional, so substitute "intentionally spilled" for "knocked".