No, not into 'lying'. It's also FRAUD! I always had a Dr's. Certificate. Back in the day, had 48weeks' sick leave in credit! Shame it couldn't be paid out! lol!
Remember many years' ago, a smart young thing 'printed' copies' of Certificates off the Internet, & was handing these in for 'sickies'. Eventually, Company 'cottoned-on' to what had/was happening & she was instantly dismissed! What a silly thing to do!