Calvin has had several adventures involving corrugated cardboard boxes, which he adapts for many different uses. In one strip, when Calvin shows off his Transmogrifier, a device that transforms its user into any desired shape, Hobbes remarks, "It's amazing what they do with corrugated cardboard these days." Calvin is able to change the function of the boxes by rewriting the label and flipping the box onto another side. In this way, a cardboard box can be used not only for its conventional purposes (a storage container for water balloons, for example), but also as a flying time machine, a duplicator or, with the attachment of a few wires and a colander, a "Cerebral Enhance-o-tron."
In the real world, Calvin's antics with his box have had varying effects. When he transmogrified into a tiger, he still appeared as a regular human child to his parents. However, in a story where he made several duplicates of himself, his parents are seen interacting with what does seem like multiple Calvins, including in a strip where two of him are seen in the same panel as his father. It is ultimately unknown what his parents do or do not see, as Calvin tries to hide most of his creations (or conceal their effects) as not to traumatize his parents.
In addition, Calvin uses a cardboard box as a desk when he is attempting to sell things. Often, Calvin's merchandise is something that no one would want, such as "suicide drink", "a swift kick in the butt" for one dollar, or a "frank appraisal of your looks" for fifty cents. In one strip, he sells "happiness" for ten cents; if one bought it, Calvin hit the person in the face with a water balloon, then revealed that he meant his own happiness. In another strip, he sold "insurance", firing a slingshot at those who refused to buy it. In some strips, he tried to sell "great ideas", and in one earlier strip, he attempted to sell the family car to obtain money for a grenade launcher. In yet another strip, he sells "life" for five cents, where the customer receives nothing in return, which, in Calvin's opinion, is life.
The box has also functioned as a secret meeting place for G.R.O.S.S., as the "Box of Secrecy".
The namespace for function names is separate from the namespace for data variables. This is a key difference between Common Lisp and Scheme. For Common Lisp, operators that define names in the function namespace include defun, flet, labels, defmethod and defgeneric.
To pass a function by name as an argument to another function, one must use the function special operator, commonly abbreviated as #'. The first sort example above refers to the function named by the symbol > in the function namespace, with the code #'>. Conversely, to call a function passed in such a way, one would use the funcall operator on the argument.
Scheme's evaluation model is simpler: there is only one namespace, and all positions in the form are evaluated (in any order) -- not just the arguments. Code written in one dialect is therefore sometimes confusing to programmers more experienced in the other. For instance, many Common Lisp programmers like to use descriptive variable names such as list or string which could cause problems in Scheme, as they would locally shadow function names.
Whether a separate namespace for functions is an advantage is a source of contention in the Lisp community. It is usually referred to as the Lisp-1 vs. Lisp-2 debate. Lisp-1 refers to Scheme's model and Lisp-2 refers to Common Lisp's model. These names were coined in a 1988 paper by Richard P. Gabriel and Kent Pitman, which extensively compares the two approaches.