be (one's) jam

slang

1. To be a song that one loves or likes a lot. Yo, this is my jam! Turn it up! A: "This dumb song is your jam?" B: "Yes, and clearly you have no taste." Look at Mom dancing with her friends over there. This must be their jam!

2. To be something that one particularly prefers, desires, enjoys, or cares about. I knew classic literature was your jam, so I thought you might like this book I found. Thank you for the invitation, but long-distance cycling just isn't really my jam. Baking's not my jam—I don't like having to measure every little thing so precisely.