Multiple Categories in a single Menu

[n0ob]

Joomla: 2.5.7
Virtuemart 2.0.18b

I want to associate multiple categories in a single menu item. Suppose I have Category1,Category2, Category3 and i want to associate all the categories to a single menu item. is it possible. all the categories are top level categories.
Those categories will have subcategories. when visitor click the menu item it will show those categories products and sub-categories products

Thanks