How to avoid evil-minded form replies

I have got a from where people can apply for membership in a club. Everyday I receive applications from sort of evil-minded people like
first name: WcrLMrJnxLwOl
family name: pJFxPjSDRprMN
address: TJnxLowhiGDdwZiywPr
The responses don't make sense, not even in my native language.
Is there a way to filter so only seemingly sensible replies go through? Sensible values are western European names.
I have tried jQuery validator:

<script>
jQuery.validator.addMethod("lettersonly", function(value, element)
{
	return this.optional(element) || /^[A-ZÅÖÄa-zåäö-]+$/i.test(value);
},
"Endast bokstäver");
$().ready(function() {
	// validate signup form on keyup and submit
	$("#signupForm").validate({
		rules: {
			fornamn: {required:true,lettersonly:true},
			efternamn: {required:true,lettersonly:true},
			adress: "required",
			postnr: {required:true,number:true},
			ort: {required:true,lettersonly:true},
			telnr: {required:true,number:true},
			mailadress: {required: true,email: true},
			stadgar: "required"
		},
		messages: {
			postnr: "&nbsp;&nbsp;<span style=\"color:#800000;\">Ange siffror utan mellanslag</span>",
			telnr: "&nbsp;&nbsp;<span style=\"color:#800000;\">Ange siffror utan mellanslag</span>",
			mailadress: "&nbsp;&nbsp;<span style=\"color:#800000;\">Glöm inte ange din e-postadress!</span>",
			stadgar: "&nbsp;&nbsp;<span style=\"color:#800000;\">Läs stadgarna och godkänn dem</span>&nbsp;"
		}
	});
});
</script>

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but the configuration I use doesn't stop people from sending me garbage.
Please help!