Yep, happened to us all!
Shortly after adopting Eva, I thought it would be cute to get a picture of her as a big lap dog... Well, after picking her up and positioning in the chair she decided (Miss Stubborn) that she wasn't a lap dog and didn't want to become one. Eva stretched and popped her head back so the top of her bony skull slammed into my forehead giving me a painful lump.
Weeks later, after she became more familiar with us and with the aid of a few treats, she complied with the photo op!
Eva Says "Dobes Not Lap Dogs" - (Except for HV Treats)
After that incident, I refer to our two Dobes as "The Knuckleheads". Spock has a real prominent occipital protuberence/sagittal
crest which could cause some real damage to another humans or animals.... Related Article- Study: Young People are Developing ?Hornlike Spikes? at Back of Their Skull Due to Poor Posture | Anatomy, Medicine | Sci-News.com