| 100% | THIRD | 5 | I Don't Know's base |
| 65% | IDK | 3 | I don't know, in text speak |
| 63% | GEE | 3 | "Hmm, I don't know!" |
| 63% | GEE | 3 | "Oh, I don't know" |
| 63% | GEE | 3 | "Hmm, I don't know" |
| 61% | GEE | 3 | "Hmm, I don't know about that" |
| 60% | ELSE | 4 | "I don't know what ___ I can do" |
| 60% | TMI | 3 | "OMG! I don't want to know that!" |
| 60% | SHE | 3 | "I Don't Know How ___ Does It" (Sarah Jessica Parker film based on an Allison Pearson novel) |
| 58% | SPAREME | 7 | "___ the details! I don't want to know!": 2 wds. |
| 58% | BASEMEN | 7 | Who, What and I Don't Know, in Abbott and Costello's "Who's on First?" routine |
| 57% | LALA | 4 | [I don't know the lyrics but I'm singing anyway] |
| 56% | WHYNOT | 6 | "Sure, I don't know any reason to avoid it": 2 wds. |
| 56% | ORA | 3 | "I don't know if it's a blessing ___ curse": 2 wds. |
| 56% | EVEN | 4 | "You Don't ___ Know Who I Am" (Patty Loveless song) |
| 56% | YOUVE | 5 | "They don't know how ___ haunted me so stunningly" |
| 56% | TELL | 4 | "___ me something I don't know!" |
| 56% | TELL | 4 | "___ me something I don't know" |
| 55% | NANCYWILSON | 11 | "(You Don't Know) How Glad I Am" singer |
| 55% | WHO | 3 | "I don't know her" |
| 55% | SHRUG | 5 | "I don't know" gesture |
| 55% | SHRUG | 5 | "I don't know" motion |
| 54% | IVE | 3 | "You don't know what ___ been through" ("Be nice to me") |
| 54% | ALOT | 4 | "There's ___ you don't know about me": 2 wds. |
| 54% | RED | 3 | "If You Don't Know Me by Now" band Simply ___ |
| 54% | SIMPLYRED | 9 | "If You Don't Know Me By Now" soul group |
| 54% | BASE | 4 | Place for Who, What, or I Don't Know |
| 54% | TMI | 3 | Texter's "I don't wanna know more!": Abbr. |
| 54% | FORSOMEREASON | 13 | "I don't know why, but . . ." |
| 54% | GEE | 3 | "I don't know" lead-in |