My guy wearing math underwear

Last Christmas, I bought my guy a pair of bamboo underwear. The pattern had math equations on it and was named smarty pants. They were fitting (pun intended), as we both like math and he is geeky. My guy told me that he loved them and wanted to change his all his underwear to be bamboo.

I have never seen him in said pair of underwear until last Saturday. I was playing with his hard cock for a while in his pants. He then undid his pants.

"I'm wearing your underwear that you got me last year," he said with a huge grin.
"Nice!" I exclaimed, touching the material before I continued playing with his member.

It's nice when he appreciates a gift that I have bought him. It was also great that I made him ejaculate all over my hand that night.

I could get him another pair. One pattern has hot dogs all over. I would love to see him in it, but I am not sure that he'd like seeing hot dogs, as he always tells me that they are bad for me to consume!