Don't be stupid. You ever heard sth. about an „active“ and a „passive“ vocabulary? Just try it.
That's why I'm trying to write in English here and also watching sometimes english spoken movies (e.g. lately Ratrace), even though I don't understand the half of it. But you can understand a lot from relationships and mimic.
BTW, don't be always such a pighead (Dickkopf). 😉
Then tell me about these active/passive vocabulary; even though I'm certain they will just as the basic vocabulary vary. Please keep in mind to not know about something has absolutely nothing to do with stupidness! Knowledge can be acquired.
Watching English movies is a good start, you can use the subtitle. I advice you to read English books and to learn those words you don't understand or know.
Pighead sounds very like an insult. You should rather use the word 'stubborn'; 'don't be so stubborn all the time'. Although I don't think that I am stubborn all the time. I'm rather persistent; having my own opinion which doesn't mean that I can't tolerate others.