A sandwich walks into a bar. This requires a certain suspension of disbelief as sandwiches are generally not ambulatory or sentient. A sandwich is in fact a food item consisting of one or more types of food placed on or between slices of bread, or more generally any dish wherein two or more pieces of bread serve as a container or wrapper for some other food. Ignore this for now and imagine that a sandwich has the ability to walk and has chosen to walk into a bar. Probably quite a large sandwich because the premise involves the barman noticing it and a small sandwich that grew small legs may walk unnoticed into a bar, especially if said bar was busy. Let’s imagine that this sandwich is the size of an average sized adult, somewhere around 5’ 8” tall perhaps.
So, a sandwich, although traditionally a non-ambulatory, non-sentient food item, consisting of one or more types of food placed on or between slices of bread, walks into a bar. This particular sandwich, as well as having the ability to walk, is also around 5’ 8” high, thus ensuring that its entrance into the bar does not go unnoticed.