Like sardines is a term used to describe a situation where people are crowded together in a confined space. The term is derived from the fact that sardines, a type of fish, are often packed tightly into tins. OILY is an appropriate word to describe sardines as they are covered in a layer of oil. Tins are the containers in which sardines are usually sold and DENSELY is an apt description of how the fish are packed into the tins.