In the style of those old "Love is..." cartoons that were popular many years ago, I cannot ever recall one that said "Love is....giving your beloved concussion".
As I write this it actually reminds me of a great big cat called Cheeky who lived in the flat upstairs who used to come calling on us most days. He was a 23yr old bruiser of a Ginger Tom with a head like a football and we adored him and his visits. He was a total Godfather character and used to do a security check round our flat until he was satisfied, before he'd accept his treats and cuddles. Despite being in his 20's and living on the third floor he'd claimed the back court as his territory almost immediately when they moved in by duffing up the locals in very short order.
Our old cat used to freak when he came in so we kept them well separated. We did try introducing them once but it didn't go well...she hissed and he walloped her...and that was the end of a beautiful relationship.
Anyway, Cheeky was good at giving very solid head bumps which my Mother hadn't twigged till the first time he stunned her and knocked her glasses off. She thought he was going to be like our little lady cat and was all affronted. My sis and I collapsed laughing because we'd both sussed that this might be his style. Every morning when Cheeky called he used to use his head to pound on the front door to let us know he wanted in....the clue was in the thud which sounded like a human knocking! Fond memories of brilliant character.