I spitted in my boss's coffee

i hate my boss, he is such a jerk Today, when he asked me to get his coffee, i did, but without him knowing, i spitted in the mug, a very big and slimy mucousy wetty spit, then poured coffee, milk and sugar, and stirred well. he was telling me later that this was the best coffee he've ever had he even asked me about the brand! i'm intending to do this everyday i'm happy now, that i'm thinking to go for the next step squeeze few drops from my tampon into his coffee, but i'm afraid it will harm him.