using UnityEngine;
using System.Collections;

public class PickUpShit : MonoBehaviour
{
    public string whattopick;

    GUIContent content;

    void Start()
    {
        content = new GUIContent("Pick up", whattopick, "[E]");
    }

    void OnGUI()
    {
        GUI.Box(new Rect(1000, 600, 100, 20), content);
    }
}

Assets/Scripts/PickUpShit.cs(12,19): error CS1502: The best overloaded method match for `UnityEngine.GUIContent.GUIContent(string, UnityEngine.Texture, string)' has some invalid arguments