My Boyfriend Woke Up This Morning With Me, And Had

my boyfriend woke up this morning with me, and had huge hickey looking marks on his shoulder and left arm. about 5 light ones on his arm and a big, prominent one on his right shoulder. we didnt notice until we were showering and i pointed it out. what could it be or how could he have gotten it over night? i never gave him a hickey due to getting a tongue piercing recently so i wouldnt have been able to suck on his arms or shoulder... please help!