I always like to stray in a context related funny slide either at the beginning or at the end of a presentation because I do not like the overall stern atmosphere at presentations.
I also planned a funny slide that is related to the topic of thesis at the end of my Bachelor thesis presentation but I am not sure If I bring myself in jeopardy through this because I assume they have to be strictly just presenting the mere content of my work and nothing else. I am even afraid that my open question to the audience (which includes Professors and Students too) at the beginning of my presentation is regarded as a violation of this strict code.