A code-word for BL (boy's love, or yaoi). In this case, it means boy on boy sex in manga/anime/fanfiction.
Also two of three ingredients in a BLT sandwitch.
I read some extremely smutty bacon lettuce yesterday.

Let me share this Shizaya bacon lettuce with you.

Mom: What is BL?
Me: ...bacon lettuce.
by Arrachne July 10, 2015
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