This type of clothing should not be worn for parties, weddings and other formal or ceremonial events. They should not also be worn for work. Various items of clothing such as tee-shirts, denims, khakis, jackets, hoodies, mini-skirts, summer dresses, loafers, sneakers, and sandals are casual wear.
The presence of a lone pair decreases the bond angle between the bonding pair of electrons, due to their high electric charge which causes great repulsion between the electrons. They are also used in the formation of a dative bond.
Basically, electron pairs in a molecule want to adopt a geometry to maximize their distance apart, since like charges repel each other. For example, methane (CH4) adopts a tetrahedral arrangement - you can think of this as the carbon atom at the center of a pyramid and the 4 hydrogens at the four vertices. Bonds angles are 109.5 degrees. This is a case where all electrons are bonding electrons; they form the 4 bonds between carbon and hydrogen. Lone electron pairs also affect the geometry. For instance, water (H2O) has two lone electrons pairs; it adopts a bent/angular geometry.