daijr:
  たわむれごと【戯れ言】たわむれて言う言葉。
  たわむれごと【戯れ事】たわむれにする事。ざれごと。

戯れ言 and 戯れ事 have different definitions. They shouldn't be merged. This entry was glossed incorrectly.
たわぶれごと appears to be archaic. I don't think it's needed.

@@ -8,8 +7,0 @@
-<keb>戯れ事</keb>
-<ke_inf>&sK;</ke_inf>
-</k_ele>
-<k_ele>
-<keb>戯事</keb>
-<ke_inf>&sK;</ke_inf>
-</k_ele>
-<k_ele>
@@ -17,4 +8,0 @@
-<ke_inf>&sK;</ke_inf>
-</k_ele>
-<k_ele>
-<keb>ざれ事</keb>
@@ -34,4 +21,0 @@
-<reb>たわぶれごと</reb>
-<re_inf>&sk;</re_inf>
-</r_ele>
-<r_ele>
@@ -43,2 +27,3 @@
-<gloss>prank</gloss>
-<gloss>practical joke</gloss>
+<gloss>joke</gloss>
+<gloss>jest</gloss>
+<gloss>gag</gloss>

たわぶれごと	0

戯言 is the headword in the たわごと and ぎげん entries. The counts will be from them. I think it's sK here.

@@ -6,3 +5,0 @@
-</k_ele>
-<k_ele>
-<keb>戯言</keb>
@@ -25,0 +23,4 @@
+<k_ele>
+<keb>戯言</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
@@ -34 +35 @@
-<re_inf>&ok;</re_inf>
+<re_inf>&sk;</re_inf>

sankoku, daijr/s, jitenon, shinkoku

Google N-gram Corpus Counts
╭─ーーー─┬───────────┬───────╮
│ 戯言　 │ 1,517,616 │ 88.6% │ not irregular
│ 戯れ言 │   183,641 │ 10.7% │
│ 戯れ事 │     5,491 │  0.3% │ add
│ 戯事　 │     3,821 │  0.2% │ add
│ ざれ言 │     2,392 │  0.1% │ add
│ ざれ事 │       138 │  0.0% │ add
╰─ーーー─┴───────────┴───────╯

added [ok] and [sk] to readings

@@ -9 +9,16 @@
-<ke_inf>&io;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>戯れ事</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>戯事</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>ざれ言</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>ざれ事</keb>
+<ke_inf>&sK;</ke_inf>
@@ -13,3 +27,0 @@
-</r_ele>
-<r_ele>
-<reb>ざれこと</reb>
@@ -21,0 +34,5 @@
+<re_inf>&ok;</re_inf>
+</r_ele>
+<r_ele>
+<reb>ざれこと</reb>
+<re_inf>&sk;</re_inf>