From a Wave (or other applicable 4-dancer formation).

Slip:

Centers Arm Turn 1/2.

Slide:

Ends and adjacent Centers slide nose-to-nose past one another to exchange places.

Swing:

Ends and adjacent Centers Arm Turn 1/2.

Slither:

Centers slide nose-to-nose past one another to exchange places.

before Slip-Slide-Swing-Slither         after Slip   after Slide   after Swing   after Slither (done)

Notes:

• Swing means 'Ends and adjacent Centers Arm Turn 1/2'. Don't confuse Swing with the Basic call Swing (your Partner). The Arm Turn 1/2 is done with the joined hand, which may be either the Right or the Left hand. Therefore, do not confuse Swing with Swing Thru, which always starts with the Right-hand.
• On Slide and Slither, dancers do not change their facing direction, since they are just sliding (nose-to-nose) with the appropriate dancer. On Slip and Swing, dancers change their facing direction by 180°.
• These are four separate calls that are not always given in the same order, but are often "stacked" (called in rapid succession). For example (from a Wave): Slip-Slide-Swing-Slither. It is the caller's responsibility to give a combination that is potentially smooth to dance. As such, there are two combinations that are often used: 1) Slip-Slide; and 2) Swing-Slither. You should be able to smoothly dance both of these combinations.
• Dancers should be able to blend adjoining calls into a smooth movement. For example, on a Slip-Slide, it is awkward to do a Slip (Centers Arm Turn 1/2), pause, then do a Slide (Ends and Adjacent Centers slide nose-to-nose). It is much smoother to blend these two calls together as follows: start the Slip, but before finishing it, Ends start to sidestep toward the center position, as Centers move forward out toward the end position before completing their final turn.
• The entire floor of dancers often verbally repeats these calls as they are dancing. This verbalization helps everyone remember which call to do next.
• From Mini-Wave Columns, the calls Slip and Slither are legal, albeit gimmicky. However, the calls Swing and Slide are not legal, since they require Ends to work with adjacent Centers.
• Swing and Slip are illegal from Facing Dancers. The dancers executing these calls must start from a Mini-Wave formation. For example, it is illegal to do a Swing from an Eight Chain Thru formation.
• From a Wave, Slide is identical to Spread [Plus].
• The calls Slip and Slither can also be done from a Diamond, Single 1/4 Tag, or a "Z". The Centers in these formations are in a Mini-Wave and can do an Arm Turn 1/2 or a slide nose-to-nose.
• Many combinations are already calls. E.g.,
  • Slip-Slide: Centers Cross Run
  • Swing-Slither: Switch The Wave
  • Slip-Slide-Slip: Mix

CONTRAST THE FOLLOWING   This is the starting formation for each of the following:     after Slip   after Centers Slip

Intending to be helpful, some callers routinely say phrases such as Centers Slip or Centers Slither when they really mean Slip or Slither, respectively. This can be misleading because normally the word 'Centers' identifies and activates the Center 4 dancers only. If the (active) Centers are not in a Wave or other applicable 4-dancer formation, then they can't do a Slip or Slither. For example, from Parallel Waves, consider the call Centers Slip: the caller identified the Centers, who are in a Box; but Slip from a Box makes no sense. Also, from formations such as Twin Diamonds or a Tidal Wave, Slip (or Slither) and Centers Slip (or Centers Slither) are different calls!