Because there are not many contexts before and after your question, you can only guess.

First, I just want to eat cold tomatoes, so I say so;

Second, metaphor, for example, if you don't want to talk to you, suddenly say this sentence, which may mean cold salad, and want to end this topic quickly;

Third, it may be just a joke. The specific judgment is whether the atmosphere at that time was relaxed and happy.

I hope I can help you ~