What's in the box, Mario?

Here we have a somewhat unusual 1983 Fleer card featuring Reds hurler Mario Soto, looking after a large, heavily scratched crate. What could be inside? Tom Seaver's hair gel? Treats for Schottzie? Schottzie? As the box is labeled #30, perhaps it is where they stored #30, Clint Hurdle, when they weren't using him (which would have been often - he only played 19 games that year).
Or perhaps Mario is keeping locked shut the demons that caused him to frequently lose his temper and get into brawls, causing him to get ejected twice in 1982.