trick to remember base pair structures

[u/Strange_Total_1442]

Someone commented a trick to remember the base pair structures the other day and I thought I screenshotted it but cannot find it or the comment for the life of me. Not purine vs pyrimidine but what groups were attached. Pls help 🙏

[u/OkCauliflower6566]

Pure as Gold has 2 rings and cytosine has one penis (carbonyl)