A group of Bowdoin students got a surprise visit last night as they were preparing to make fundraising calls to parents and alumni. President Barry Mills stopped by the call center for a pep talk and to issue a personal challenge to the student callers. Mills promised to take the whole group to dinner in Brunswick-on him-if they meet their goals. Eleven student callers hope to connect with 1,900 alumni donors plus hundreds of parents between now and June 30, 2012.