| I can tell you | | | |
| I can't hear you over the sound of | | | |
| I can't lie | | | |
| ice-calm | | | |
| ice-cold | | | |
| ice cool | | | |
| ice maiden | | | |
| ice queen | | | |
| I choose violence | | | |
| icing on the cake | | | |
| I could eat a horse | | | |
| idiot box | | | |
| idiot mittens | | | |
| I'd like to see someone try | | | |
| I don't fancy yours | | | |
| I don't know about that | | | |
| I'd say | | | |
| if anything | | | |
| I fear | | | |
| if I'm honest | | | |
| if I'm not there, start without me | | | |
| if it's all the same | | | |
| if it works, it works | | | |
| if need be | | | |
| if needs be | | | |
| if nothing else | | | |
| if only | | | |
| if pigs had wings | | | |
| if these walls could talk | | | |
| if the shoe fits | | | |
| if the shoe fits, wear it | | | |
| I hardly know her | | | |
| I have a bridge to sell you | | | |
| I just work here | | | |
| I'll be | | | |
| I'll be a monkey's uncle | | | |
| I'll be bound | | | |
| I'll be damned | | | |
| I'll be danged | | | |
| ill health | | | |
| I'll say | | | |
| I'll tell you | | | |
| I'm not being funny | | | |
| I'm not telling you | | | |
| I'm not the one | | | |
| I'm sure | | | |
| I'm telling you | | | |
| in a bake | | | |
| in a big way | | | |
| in a bind | | | |
| in a box | | | |
| in Abraham's bosom | | | |
| in a bubble | | | |
| in a corner | | | |
| in addition | | | |
| in a fix | | | |
| in a flash | | | |
| in a foam | | | |
| in a fog | | | |
| in a heartbeat | | | |
| in a hen's hiney | | | |
| in a jam | | | |
| in a league of one's own | | | |
| in all honesty | | | |
| in all modesty | | | |
| in all one's glory | | | |
| in a major key | | | |
| in a mess | | | |
| in a minor key | | | |
| in and of itself | | | |
| in and out | | | |
| in a nutshell | | | |
| in any case | | | |
| in any event | | | |
| in any way, shape, or form | | | |
| in a pickle | | | |
| in a pig's arse | | | |
| in a pig's eye | | | |
| in a pig's patoot | | | |
| in a pinch | | | |
| in a real state | | | |
| in a right state | | | |
| in a rut | | | |
| in a snap | | | |
| in a state | | | |
| in at the deep end | | | |
| in a walk | | | |
| in bad odor | | | |
| in bad shape | | | |
| in bad taste | | | |
| in bed | | | |
| in black and white | | | |
| in business | | | |
| in capital letters | | | |
| inch along | | | |
| in character | | | |
| inch away | | | |
| inch back | | | |
| inch by inch | | | |
| inch forward | | | |