A surprise party is a celebration that is not made known to one or more of the guests until it occurs.
There are several types of surprise parties, honoring different things or people:
Surprising a new mother and her child is a common type of surprise party. "Mom" "Mum" and "Mommy" redirect here The baby shower surprise party should have all the elements of a regular baby shower, including gifts and food. A baby shower is a Party in which parents or expectant parents receive Gifts for their newborn or expected child Unlike normal baby showers, however, a baby shower surprise party should be held with only informal attire, because the honored mother would probably not show up to the party wearing a black dress.  The surprise party should also make sure to keep the noise level down so the baby is not upset.
Birthday surprise parties are most common. Birthday is the name given to the date of the anniversary of a person's birth At most birthday surprise parties, guests arrive approximately one hour earlier than the honored person does. They assume hiding positions, and as the honored person walks in the front door, everyone emerges from their hiding positions, yelling "Surprise!"
For many surprise birthday parties, it is generally considered a good tactic to shock the honored person. Streamers, silly string, and balloons can be used to great effect. Streamers is a play by David Rabe The production transferred to Broadway, opening on April 21 1976 at Lincoln Center 's Mitzi Silly String is a child's toy generically known as aerosol string: a flexible brightly-colored plastic string which is shot as a stream of liquid from an Aerosol can A balloon is a flexible bag filled with a type of Gas, such as Helium, Hydrogen, Nitrous oxide or air. All evidence of a party, like decorations, should not be visible from the outside (as a giveaway). 
There are some disadvantages to this method of birthday celebration. For example, the honored person may feel ignored because their birthday is not mentioned until the party occurs. A party is a Social gathering for Celebration and Recreation. Also, if the honored person does not appreciate the surprise effect, they may become angry or disgruntled.  In addition, the honored person may not be appropriately dressed for the occasion, and may feel out of place in frumpy, casual clothing compared to the other dressed guests. Finally, the sudden emotional stress caused by a surprise party can cause stress cardiomyopathy. Takotsubo cardiomyopathy, also known as transient apical ballooning, apical ballooning cardiomyopathy, stress-induced cardiomyopathy and simply stress