[FergusArgyll]

Steven Pinker's book on irregular verbs has a great example of this.

little kids often mess up on irregular verbs ("I eated supper") because they (subconsciously?) learn the grammar, they aren't memorizing the past tense of every word

[dazc]

The beauty of English being that everyone understands what the kid meant.

[footy]

This is true of every language though. Language acquisition works like this (and people understand what young children mean) regardless of whether you're learning English or Spanish or German or Korean.

[adhesive_wombat]

I think in German some smashed up sentence like "ich haben gegesst der Abendessen" would also be understandable no matter how brutally you fluff the verb's conjugation and gender of the noun.