I was so busy I forgot to buy a train station bento.
One fun thing to do during domestic trips in Japan is to compare various station bento.
Oh, you forgot to bring the onigiri? We’ll have to buy a station bento for lunch.
Remember how 弁当 is "bento"? Well, the 弁 in this word comes from that, so pretend it means "bento." Then, when you have a train station to go along with the bento, you have a train station bento. As you might think, a train station bento is just a bento that's sold at a train station. Easy!
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.