It's not often that you get locked out of your own iPhone after you enter the wrong passcode. But it can happen in houses where kids and others try to unlock your iPhone. Once someone enters the wrong passcode multiple times, you can't unlock your iPhone for some time.
This can last anywhere between 1 minute to 60 minutes and when it happens, it really sucks. You can't even do anything even if you know the right passcode that will unlock the device. While you can't get out of this fix once you get in it, there's a way you can prevent the lockout feature on your iPhone.
Prevent Passcode Failed Attempts from Locking Your iPhone with disabled Cydia tweak
A Cydia tweak developed by Javier Brito aims to disable this feature. Interestingly, the tweak is called disabled and it will prevent your iPhone from locking you out after the ten failed passcode attempts.
There is absolutely nothing to tweak / change once you have installed the tweak. Head over to Settings → disabled and enable the switch for Activate. This will disable the iOS feature which locks out the iPhone for a specific time after a set number of failed passcode attempts.
We tried this with Restriction passcode but it didn't work so the tweak seems to be for lockscreen passcode only. But it's enormously useful if you've got kids around who'll try to unlock your iPhone when you are away from it.
‘disabled' also has one more switch (Bypass). What this does is simple: it lets you access particular apps from the Notification Center on lockscreen without having to enter the passcode. This is a security-breach actually and is not recommended at all but in rare use-cases, this might be a useful option. It will still not let you access Mail) but every other notification can be opened in its app without entering the passcode.
‘disable' is available for free on Cydia's BigBoss repo.