Quadrennial occasion celebrated by this puzzle's theme entries

Question:

Answer:

LEAPDAY

Length:

Similar Crossword Questions:

Like fish for fish & chips -- or this puzzle's four theme entries
Tone-Loc and Marky Mark and the Funky Bunch, e.g. ... or how this puzzle's theme entries might be described?
What the names in this puzzle's theme entries begin with
Make of six models that are subject to recall ... and being sent back inside this puzzle's theme entries
"Infections" inside this puzzle's theme entries
The three of this puzzle's theme entries
Physical principle whose equation explains the changes in this puzzle's theme entries
Like some fillings (as in this puzzle's theme entries)
What this puzzle's theme entries probably do?
First of a pair of letters swapped six times in this puzzle's theme entries
Find new work - or what you must do to get the three theme entries' names in this puzzle
Challenged, or what the theme entries in this puzzle should be
This puzzle's theme entries
Event celebrated in this puzzle, and an example of how the theme works
They're hidden in this puzzle's theme entries
Second of a pair of letters swapped six times in this puzzle's theme entries
What the constructor had to do to create the theme entries in this puzzle (boyeee)
What the three theme entries in this puzzle are, in either of two ways
Playoff series finale ... or an apt title for this puzzle considering the number and length of its theme entries
This puzzle's theme entries, e.g.
Office building problem that's a hint to this puzzle's theme entries (see their last three letters)
Many people get one in the summer (and so do this puzzle's theme entries)
What this puzzle's theme entries are
"Lid" in each of this puzzle's theme entries
Activity suggested by this puzzle's theme entries